This document is the title page and copyright information for the Webster's New World Medical Dictionary, Third Edition. It provides information on the copyright, permissions, disclaimers, trademarks, and publishing details for the medical dictionary. The acknowledgments section thanks the staff at WebMD and Wiley Publishing for their work on developing the dictionary. Biographies of the editors are also included.
6. Acknowledgments
At MedicineNet.com, a part of the WebMD network, we continue to foster the concept that you, the
readers, are truly interested in understanding health issues and medical concepts. Accordingly, we
have addressed the medical terms in this dictionary with sensitivity to potential concerns of those
who are acutely or chronically confronting disease or health concerns. We are grateful for your
interest in health topics as it is a driving force for the development of the Webster’s New World
Medical Dictionary, Third Edition.
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The excellence of the technical and editorial staffs at MedicineNet.com greatly facilitated this entire
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been an inspirational catalyst for motivation and consistent superior quality.
William C. Shiel, Jr., MD, FACP, FACR, thanks his children, Cara Shiel Krenn, Daniel, and Timothy for
their support. He also acknowledges the support and encouragement of his parents, William and
Virginia Shiel, as well as his dear mother-in-law, Helen Stark. With infinite gratitude and love he
thanks his wife, Catherine, for her support, love, and editing. With gratitude he acknowledges the
Herculean efforts of Frederick Hecht, MD, FAAP, FACMG in developing previous editions of this dic-
tionary. And, with admiration beyond words, he thanks his dear friend, colleague, and co-founder
of MedicineNet.com, Dennis Lee, MD.
Melissa Conrad Stöppler, MD wishes to thank her husband, Hubert Stöppler, and her children,
Johannes, Anna, and Tilman, for their enduring support, love, and patience. She also gratefully
acknowledges the support and encouragement of her parents, Kathryn B. Conrad and the late Henry
E. Conrad, Jr.
Thank you all.
–William C. Shiel, Jr., MD, FACP, FACR
–Melissa Conrad Stöppler, MD
7. Get Additional Free Content Online
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Editorial Staff
Co-Editors-in-Chief Ruchi Mathur, MD, FRCP(C)
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8. About the Authors
William C. Shiel, Jr., MD, FACP, FACR, Co-Editor-in-Chief
William C. Shiel, Jr., MD, FACP, FACR, received a bache-
lor of science degree with honors from the University of
Notre Dame. There he was involved in research in radi-
ation biology and received the Huisking Scholarship.
After graduating from St. Louis University School of
Medicine, he completed his internal medicine resi-
dency and rheumatology fellowship at University of
California, Irvine. He is board certified in internal med-
icine and rheumatology and is a fellow of the American
Colleges of Physicians and Rheumatology. Dr. Shiel is in
active practice in the field of rheumatology at the
Arthritis Center of Southern Orange County, California.
He is currently an active associate clinical professor of
medicine at University of California, Irvine. He has
served as chair of the Department of Internal Medicine at Mission Hospital Regional Medical Center
in Mission Viejo, California. Dr. Shiel has authored numerous articles on subjects related to arthri-
tis for prestigious peer-reviewed medical journals, as well as many expert medical-legal reviews. He
has lectured in person and on television both for physicians and the community. He is a contribu-
tor for questions for the American Board of Internal Medicine and has reviewed board questions on
behalf of the American Board of Rheumatology Subspecialty. He served on the Medical and Scientific
Committee of the Arthritis Foundation, and he is currently on the Medical Advisory Board of Lupus
International. Dr. Shiel is proud to have served as chief editor for MedicineNet.com since its found-
ing in 1996. He was co-editor-in-chief of the first and second editions of Webster’s New World
Medical Dictionary.
9. Melissa Conrad Stöppler, MD, Co-Editor-in-Chief
Melissa Conrad Stöppler, MD, is a US board-certified
anatomic pathologist with subspecialty training in the
fields of experimental and molecular pathology. Dr.
Stöppler’s educational background includes a BA with
Highest Distinction from the University of Virginia and
an MD from the University of North Carolina. She com-
pleted residency training in anatomic pathology at
Georgetown University followed by subspecialty fellow-
ship training in molecular diagnostics and experimen-
tal pathology. Dr. Stöppler served as a faculty member
of the Georgetown University School of Medicine and
has also served on the medical faculty at the University
of Marburg, Germany. Her research in the area of virus-
induced cancers has been funded by the National
Institutes of Health as well as by private foundations. She has a broad list of medical publications,
abstracts, and conference presentations and has taught medical students and residents both in the
United States and Germany. Dr. Stöppler was named a fellow of the Alexander von Humboldt Society
in Germany and was a recipient of a Physician Scientist Award from the US National Cancer Institute.
Dr. Stöppler currently serves on the Medical Editorial Board of MedicineNet.com, and is the Chief
Medical Editor of eMedicineHealth.com, both WebMD Inc. companies. Her experience also includes
translation and editing of medical texts in German and English. Dr. Stöppler’s special interests in
medicine include family health and fitness, patient education/empowerment, and molecular diag-
nostic pathology. She currently resides in the San Francisco Bay area with her husband and their
three children.
Dennis Lee, MD, Assistant Editor
Dennis Lee, MD, was born in Shanghai, China, and received his college and medical training in the
United States. He is fluent in English and three Chinese dialects. He graduated with chemistry depart-
mental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA
School of Medicine. He underwent internal medicine residency and gastroenterology fellowship
training at Cedars-Sinai Medical Center. Board certified in internal medicine and gastroenterology,
Dr. Lee is currently a member of Mission Internal Medical Group, a multispecialty medical group
serving southern Orange County, California. Dr. Lee has maintained an interest in technology and
medical education. He is a regular guest lecturer at Saddleback College in Orange County, California.
Dr. Lee serves as chair of MedicineNet.com.
10. Jay W. Marks, MD, Assistant Editor
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale
University School of Medicine and trained in internal medicine and gastroenterology at
UCLA/Cedars-Sinai Medical Center in Los Angeles. For 20 years he was associate director of the
Division of Gastroenterology at Cedars-Sinai Medical Center and an associate professor of medicine,
in residence, at UCLA. At Cedars-Sinai he co-directed the Gastrointestinal Endoscopy Unit, taught
physicians during their graduate and postgraduate training, and performed specialized, nonendo-
scopic gastrointestinal testing. He carried out Public Health Service–sponsored (National Institutes
of Health) clinical and basic research into mechanisms of the formation of gallstones and methods
for the nonsurgical treatment of gallstones. He is the author of 36 original research manuscripts and
24 book chapters. Dr. Marks presently directs an independent gastrointestinal diagnostic unit where
he continues to perform specialized tests for the diagnosis of gastrointestinal diseases. Dr. Marks
serves as medical and pharmacy editor of MedicineNet.com.
Ruchi Mathur, MD, FRCP(C), Assistant Editor
Dr. Mathur received her medical degree in Canada and did her medical residency at the University
of Manitoba in Internal Medicine. Dr. Mathur is a certified fellow of the Royal College of Physicians
of Canada and is US board certified in internal medicine and endocrinology, diabetes and metabo-
lism. She has been the recipient of numerous research grants which have included the American
Diabetes Association grant for research in the field of diabetes and gastric dysmotility and the
Endocrine Fellows Foundation Grant for Clinical Research. She has an extensive list of medical pub-
lications, abstracts, and posters and has given numerous lectures on diabetes. Most recently she has
co-authored the textbook Davidson’s Diabetes Mellitus: Diagnosis and Treatment, published by
Elsevier. Dr. Mathur has also served as Research Fellow at Cedars-Sinai Medical Center and a clini-
cal instructor at UCLA in endocrinology and metabolism. Currently Dr. Mathur is Co-Director of the
Diabetes Management Clinic at the Roybal Comprehensive Health Center and Assistant Professor of
Medicine at the Keck School of Medicine, University of Southern California.
Contributing Authors
Ronald Adamany, MD, Gastroenterology • Kent Adamson, MD, Orthopedic Surgery • Leon Baginski,
MD, Obstetrics & Gynecology • Jerry Balentine, DO, FACOEP, FACEP, Emergency Medicine • Edward
Block, MD, Gastroenterology • James Bredencamp, MD, Otolaryngology • Yuri Bronstein, MD,
Neurology • Rudolph Brutico, MD, Pediatrics • Carolyn Janet Crandall, MD, Internal Medicine &
Women’s Health • Howard Crystal, MD, Neurology • John Cunha, DO, Emergency Medicine • Eric
Daar, MD, Internal Medicine & Infectious Diseases • Andrew A. Dahl, MD, FACS, Opthamology •
11. Fernando Dangond, MD, Neurology • Charles C.P. Davis, MD, PhD, Emergency Medicine • Roxanne
Dryden-Edwards, MD, Psychiatry and Mental Health • Jason C. Eck, DO, MS, Orthopaedic Surgery •
Steve Ehrlich, MD, Cardiology • Manuel Fernandez, MD, Endocrinology • Robert Ferry, MD,
Pediatric Endocrinologist • Michael C. Fishbein, MD, Cardiovascular & Autopsy Pathology • Tse-Ling
Fong, MD, Hepatology • Catherine G. Fuller, MD, Allergy & Immunology • Ronald Gehling, MD,
Allergy & Immunolgy • Gus Gialamas, MD, Orthopedic Surgery • Gary W. Gibbon, MD, Pulmonary
Disease & Allergy • Mitchell J. Gitkind, MD, Gastroenterology • Vay Liang W. Go, MD, Nutrition •
Sandra Gonzalez Gompf, MD, FACP, FIDSA, Infectious Disease • Jayson Goo, ATC, MA, CKTI, Human
Performance/Corrective Therapy • Daniel L. Gomel, MD, Internal Medicine & Geriatrics • Mark
Graber, MD, Family Practice • Harold H. Harsch, MD, Psychiatry • Roza Hayduk, MD, Sleep
Medicine • Barbara K. Hecht, PhD • Frederick Hecht, MD, FAAP • Standiford Helm III, MD,
Anesthesiologist/Pain Management • Kendall Ho, MD, Emergency Medicine • Debra E. Houry, MD,
MPH, Emergency Medicine/Women’s Health • Camille Marie Teres Hylton, MD, Ophthamology •
David Kaminstein, MD, Gastroenterology • Kenneth Kaye, MD, Pathology • Jillyen E. Kibby, M.A.,
CCC-A, Audiology • Harley J. Kornblum, MD, Pediatrics & Neurology • Betty Kovacs, MS, RD,
Nutrition • Daniel Lee Kulick, MD, FACC, FSCAI., Internal Medicine & Cardiology • Eric Lee, MD,
Gastroenterology • Margaret Lee, DDS, Dentistry • Stacy E. Lee, MD, Allergy & Immunology •
Michael Lill, MD, Hematology/Oncology • Arthur H. Loussararian, MD, Inetrnal Medicine &
Cardiology • Ralph Maeda, MD, Surgery • Dwight Makoff, MD, Nephrology & Hypertension •
Murray Margolis, MD, Internal Medicine • Randy Martin, MD, Pulmonary/Infectious Diseases •
James Meaglia, MD, Urology • John Mersch, MD, Pediatrics • Michael Miyamoto, MD, Cardiology •
Zab Mohsenifar, MD, Internal Medicine & Pulmonary Diseases • John R. Morris, MD, Orthopedic
Surgery • Mim Mulford, MD, Endocrinology • Marty Nettleman, MD, MS, Infectious Disease • Mark
Scott Noah, MD, Internal Medicine • Omudhome Ogbru, PharmD, Pharmacy • Peter J. Panzarino,
Jr. MD, Psychiatry & Behavioral Medicine • David Adam Perlstein, MD, FAAP, Pediatarics • Dennis
Philips, MD, Pediatrics • Donald Pratt, MD, Internal Medicine • Stefan M. Pulst, MD, Neurology •
J. Bradley Randleman, MD, Opthamology • Donald Rediker, MD, Cardiology • Alan Rockoff, MD,
Dermatology • Emmanuel Saltiel, PharmD FASHP, FCCP, Pharmacy • Stephen J. Sanders, M.A., CCC-A,
Audiology • Michael Santoro, MD, Gastroenterology • George Schiffman, MD, Pulmonary • Leslie
J. Schoenfield, MD, PhD • Melvin Shiffman, MD, Cosmetic Surgery • Lawrence J. Schwartz, MD,
Ophthalmology • Joseph Sciammarella, MD, FACP, FA.CEP, Emergency Medicine • John Sheppard,
MD, Ophthalmology and Pharmacology • David Simon, MD, Internal Medicine • Robert Simon, MD,
Neurology • Thomas P. Sokol, MD, FACS, FASCRS, Gastroenterology • Mark Sullivan, MD, Urology •
Alan Szeftel, MD, Allergy and Immunology/Pulmonary Disease • Bruce Tammelin, MD, Pulmonary
Disease • Suzanne Trupin MD, FACOG, Obstetrics and Gynecology • Michael Truong, MD,
Endocrinology • Theodore Van Dam, MD, Internal Medicine • John Vierling, MD, Hepatology •
Benjamin C. Wedro, MD, FAAEM, Emergency Medicine • Richard Weil, M.Ed., CDE, Exercise
Physiology, Diabetes Educator • Maureen Welker, MSN, NPc, CCRN • Edward J. White, MD, General
Surgery • Leslie Williams, EdD, Psychology • Joseph Y. Wu, MD, Internal Medicine & Geriatrics •
Marilyn A.D. Yee, PharmD, Pharmacy • David Zachary, MD, Family Medicine
12. Introduction
lexicographer A writer of dictionaries, a harmless drudge.
–Samuel Johnson, 1755
Like the previous editions, this edition has been conceived and developed by the staff of the health
information Web site MedicineNet.com, part of the WebMD Health Network. One of the earliest
health information sites on the Internet, MedicineNet.com has devoted a number of years to creat-
ing an online medical dictionary that now contains a wealth of contemporary medical terms and
provides the broad foundation for this book.
To create this new edition of Webster’s New World Medical Dictionary, we have reviewed every
entry in the previous edition and have rewritten and strengthened many of those entries. In addition,
we have selected new entries from our online medical dictionary for incorporation into this third
edition. A unique feature of an online medical dictionary is that it can (and does) evolve rapidly to
keep pace with the changes in medicine. We have taken advantage of this to update Webster’s New
World Medical Dictionary.
Like all of the medical content from MedicineNet.com, this dictionary was written and edited by
physicians, to be used by anyone and everyone concerned about their own health or the health of
those who matter to them. All the medical information found on MedicineNet.com has been devel-
oped by a network of physicians. The physicians select the topics and review and edit all written con-
tent. These physicians also make use of medical specialists and health writers throughout the US.
The “About the Authors” pages provide abbreviated biographies of the editors and specialists who
contributed content to the MedicineNet.com online dictionary and this book.
Medicine is now advancing with remarkable rapidity on many fronts, and the language of medi-
cine is also continually evolving with remarkable rapidity, commensurate with the changes. Today,
there is constant need for communication between and among consumers and providers of health
care. There is consequently a need for a high-quality, contemporary medical dictionary.
In the current health care environment, patients and their physicians, nurses, and allied health pro-
fessionals must be able to discuss the ever-changing aspects of health, disease, and biotechnology.
An accurate understanding of medical terminology can assist communication and improve care for
patients, and it can help to alleviate the concerns of family members and friends.
The fact that the content of this dictionary is physician-produced by MedicineNet.com ensures an
unusual degree of professional expertise, reliability, and perspective.
13. As a bonus, this edition includes a companion Web site at www.medterms.com/wnw. There you will
find content not found in the book such as PDF healthcare guides and audio podcasts.
We hope that you will find Webster’s New World Medical Dictionary, Third Edition a valuable addi-
tion to your family or office library and a source of both information and illumination in any med-
ical situation.
14. that spans the body cavity, just below the lungs. See
Aa
also abdominal cavity.
abdomen, acute See acute abdomen.
abdominal aorta The final section of the aorta,
the largest artery in the body, which begins at the
diaphragm as a continuation of the thoracic aorta
and ends by splitting in two, to form the common
iliac arteries. The abdominal aorta supplies oxy-
genated blood to all the abdominal and pelvic
organs, as well as to the legs. See also aorta.
A In genetics, adenine, a member of the adenine- abdominal aortic aneurysm See aneurysm,
thymine (A-T) base pair in DNA. abdominal aortic.
a- Prefix indicating the absence or depletion of abdominal cavity The cavity within the
something: for example, aphagia (not eating) or abdomen. This space between the abdominal wall
aphonia (voiceless). The related prefix an- is usu- and the spine contains a number of crucial organs,
ally used before a vowel, as in anemia (without including the lower part of the esophagus, the stom-
blood) and anoxia (without oxygen). ach, small intestine, colon, rectum, liver, gallblad-
der, pancreas, spleen, kidneys, adrenal glands,
AA 1 Alcoholics Anonymous. 2 Amino acid. ureters, and bladder. See also abdomen.
AAAS American Association for the Advancement abdominal guarding Tensing of the abdominal
of Science, a professional organization that pub- wall muscles to guard inflamed organs within the
lishes the weekly journal Science. abdomen from the pain of pressure upon them.
AAFP 1 American Association of Family Abdominal guarding is detected when the abdomen
Physicians, a professional organization for physi- is pressed and is an indication that inflammation of
cians who treat both children and adults. 2 the inner abdominal (peritoneal) surface may be
American Academy of Family Physicians, a profes- present due, for example, to appendicitis or diverti-
sional organization for physicians who treat both culitis. The tensed muscles of the abdominal wall
children and adults. automatically go into spasm to keep the tender
underlying tissues from being irritated.
AAO 1 American Association of Ophthalmology, a
professional organization. 2 American Association abdominal hysterectomy See hysterectomy,
of Orthodontists, a professional organization. 3 abdominal.
American Academy of Otolaryngology, a professional abdominal muscle One of a large group of mus-
organization. cles in the front of the abdomen that assists in main-
AAOS American Academy of Orthopaedic taining regular breathing movements, supports the
Surgeons, a professional organization. See also muscles of the spine while lifting, and keeps abdom-
orthopaedics. inal organs in place. Abdominal muscles are the tar-
get of many exercises, such as sit-ups. Abdominal
AAP 1 American Academy of Pediatrics, a profes- muscles are informally known as the abs.
sional organization for physicians who treat
infants, children, adolescents, and young adults. abdominal pain Pain in the belly. Abdominal
2 American Academy of Pedodontics, a professional pain can be acute or chronic. It may reflect a major
organization. 3 American Academy of problem with one of the organs in the abdomen,
Periodontology, a professional organization. 4 such as appendicitis or a perforated intestine, or it
American Association of Pathologists, a professional may result from a fairly minor problem, such as
organization. excess buildup of intestinal gas.
ab- Prefix indicating from, away from, or off, as in abducens nerve See abducent nerve.
abduction (movement of a limb away from the mid- abducent nerve The sixth cranial nerve, which
line of the body) and abnormal (away from normal). emerges from the skull to operate the lateral rectus
abdomen The part of the body that contains all muscle. This muscle draws the eye toward the side
the structures between the chest and the pelvis. The of the head. Paralysis of the abducent nerve causes
abdomen, or belly, is anatomically separated from inward turning of the eye.
the chest by the diaphragm, the powerful muscle
15. abduction 2
abduction The movement of a limb away from abortion, spontaneous Miscarriage.
the midline of the body. The opposite of abduction
is adduction. abortive Tending to cut short the course of a dis-
ease, as in abortive polio (polio cut short).
abductor muscle See muscle, abductor.
abortive polio A minor, abbreviated form of
ABG Arterial blood gas, a sampling of the blood infection with the polio virus. Full recovery occurs
levels of oxygen and carbon dioxide within the in 24 to 72 hours, and the condition does not
arteries, as opposed to the levels of oxygen and car- involve the nervous system or permanent disabili-
bon dioxide in veins. Typically, the acidity (pH) is ties. See also polio.
also simultaneously measured.
ABP American Board of Pediatrics, a professional
abiotrophy Loss of function, or degeneration for organization for physicians who treat infants, chil-
reasons unknown. dren, adolescents, and young adults.
ablate To remove, from a Latin word meaning “to abrasion 1 A wearing away of the upper layer of
carry away.” See ablation. skin as a result of applied friction force. See also
scrape. 2 In dentistry, the wearing away of a tooth
ablation Removal or excision. Ablation is usually surface.
carried out surgically. For example, surgical
removal of the thyroid gland (a total thyroidectomy) abruptio placentae Premature separation
is ablation of the thyroid. (abruption) of the placenta from the wall of the
uterus, often in association with high blood pres-
abnormal Outside the expected norm, or sure or preeclampsia. Abruption is a potentially
uncharacteristic of a particular patient. serious problem both for mother and fetus because
the area where it occurs bleeds and the uterus
ABO blood group The major human blood begins to contract. Shock may result. See also pla-
group system. The ABO type of a person depends on centa; preeclampsia.
the presence or absence of two genes, A and B.
These genes determine the configuration of the red abs Slang term for the abdominal muscles.
blood cell surface. A person who has two A genes
has red blood cells of type A. A person who has two abscess A local accumulation of pus anywhere in
B genes has red cells of type B. If the person has one the body. See also boil; pus.
A and one B gene, the red cells are type AB. If the
person has neither the A nor the B gene, the red abscess, perianal An abscess next to the anus
cells are type O. It is essential to match the ABO sta- that causes tenderness, swelling, and pain on defe-
tus of both donor and recipient in blood transfu- cation.
sions and organ transplants.
abscess, peritonsillar An abscess behind the
abortifacient A medication or substance that tonsils that pushes one of the tonsils toward the
causes pregnancy to end prematurely. uvula (the prominent soft tissue dangling from the
back of the palate in the back of the mouth). A peri-
abortion Premature exit of the products of the tonsillar abscess is generally very painful and asso-
fetus, fetal membranes, and placenta from the ciated with difficulty opening the mouth. If a
uterus. Abortion can be a natural process, as in a peritonsillar abscess is untreated, the infection can
miscarriage; an induced procedure, using medica- spread deep into the neck, causing airway obstruc-
tion or other substances that cause the body to tion and other life-threatening complications.
expel the fetus; or a surgical procedure that
removes the contents of the uterus. See also dila- abscess, skin A confined collection of pus in the
tion and curettage. skin. The common boil is a type of skin abscess. See
also boil.
abortion, habitual The miscarriage of three or
more consecutive pregnancies with no intervening abscission To remove tissue by cutting it away, as
pregnancies. Habitual abortion is a form of infertil- in surgery. See also resection.
ity. Also known as recurrent abortion and multiple
abortion. absence of the breast See amastia.
abortion, multiple See abortion, habitual. absence of the nipple See athelia.
abortion, recurrent See abortion, habitual.
16. 3 ACE inhibitor
absinthe An emerald-green liqueur flavored with accessory nerve The eleventh cranial nerve,
extracts of the wormwood plant, licorice, and aro- which emerges from the skull and receives an addi-
matic flavorings in an alcohol base. Absinthe was tional (accessory) root from the upper part of the
manufactured, commercialized, and popularized in spinal cord. It supplies the sternocleidomastoid and
France in the late 1700s. It was an extremely addic- trapezius muscles.
tive drink. Prolonged drinking of absinthe causes
convulsions, blindness, hallucinations, and mental accessory neuropathy A disease of the acces-
deterioration. Absinthe has been banned, but some- sory nerve, paralysis of which prevents rotation of
thing of its taste is still available in such drinks as the head away from one or both sides and causes
Greek ouzo and French pastis. Homemade absinthe the shoulder to droop. Damage can be confined to
may still be illicitly consumed in some areas. the accessory nerve, or it may also involve the ninth
and tenth cranial nerves, which exit the skull
absolute CD4 count The number of “helper” T- through the same opening.
lymphocytes in a cubic millimeter of blood. The
absolute CD4 count is frequently used to monitor accessory placenta See placenta, accessory.
the extent of immune suppression in persons with
HIV because with HIV, this number declines as the acclimatization to altitude The process of
infection progresses. Also known as T4 count. adapting to the decrease in oxygen concentration at
a specific altitude. A number of changes must take
absorption Uptake. For example, intestinal place for the body to operate with decreased oxy-
absorption is the uptake of food (or other sub- gen. These changes include increasing the depth of
stances) from the digestive tract. respiration; increasing the pressure in the pul-
monary arteries, forcing blood into portions of the
abstinence The voluntary self-denial of food, lung that are normally not used at sea level; manu-
drink, or sex. Today, abstinence most commonly facturing additional oxygen-carrying red blood
refers to denial of one’s sexual activity. cells; and manufacturing extra 2, 4-DPG, a sub-
stance that facilitates the release of oxygen from
abuse, child See child abuse. hemoglobin to the body tissues. Acclimatization
generally takes 1 to 3 days and occurs after any
abuse, elder See elder abuse. significant altitude change above 1,220 meters
(approximately 4,000 feet). Acclimatization is the
a.c. Abbreviation of the Latin phrase ante cibum, body’s natural means of correcting altitude sickness
meaning “before meals.” See also Appendix A, and the rate of acclimatization depends on the alti-
“Prescription Abbreviations.” tude, rate of ascent, and individual susceptibility.
AC joint See acromioclavicular joint. accoucheur A male obstetrician. An
accoucheuse is a woman obstetrician, or sometimes
acanthosis nigricans A skin condition charac- a midwife.
terized by dark, thickened, velvety patches, espe-
cially in the folds of skin in the armpit, groin, and ACE Angiotensin converting enzyme. ACE converts
back of the neck. It can occur with endocrine dis- an angiotensin to its activated form, angiotensin II,
eases such as Cushing disease and diabetes mellitus, enabling it to function. Angiotensin II constricts
from tumors of the pituitary gland, underlying malig- blood vessels and elevates blood pressure.
nancies, certain drugs, and as a genetic disorder. It
is most common in people who have insulin resist- ACE inhibitor A drug that inhibits ACE. Using an
ance—those whose body is not responding cor- ACE inhibitor relaxes the arteries, not only lowering
rectly to the insulin that they make in their pancreas. blood pressure but also improving the pumping effi-
ciency of a failing heart and improving cardiac out-
acapnia Lower than normal level of carbon dioxide put in patients with heart failure. ACE inhibitors are
in the blood. The opposite of acapnia is hypercapnia. therefore used for blood pressure control and con-
gestive heart failure. ACE inhibitors include
accelerated phase of leukemia Chronic myel- benazepril (brand name: Lotensin), captopril
ogenous leukemia that is progressing. In this phase, (brand name: Capoten), lisinopril (brand names:
the number of immature, abnormal white blood Zestril, Prinivil), quinapril (brand name: Accupril),
cells in the bone marrow and blood is higher than and ramipril (brand name: Altace). Interestingly,
in the chronic phase, but not as high as in the blast ACE inhibitors were originally developed from the
phase. venom of a Brazilian viper snake.
17. acentric chromosome 4
acentric chromosome A chromosome that is Achilles tendon One of the longest tendons in
lacking a centromere (a specialized region of the the body, a tough sinew that attaches the calf muscle
chromosome to which spindle fibers attach during to the back of the heel bone (calcaneus). The name
cell division). As a result, an acentric chromosome comes from Greek mythology: The hero Achilles
is lost when the cell divides. See also centromere. was invulnerable to injury except for his heel, which
proved his downfall when it was pierced by Paris’s
aceruloplasminemia See ceruloplasmin arrow. It has also proved, literally, to be the down-
deficiency. fall of many athletes who have experienced the sud-
den pain of its rupture.
acetabulum The cup-shaped socket of the hip
joint. The acetabulum is a feature of the pelvis. The Achilles tendonitis Inflammation in the tendon
head (upper end) of the femur (thighbone) fits into of the calf muscle, where it attaches to the heel
the acetabulum and articulates with it, forming a bone. Achilles tendonitis causes pain and stiffness at
ball-and-socket joint. the back of the leg, near the heel. Achilles tendonitis
can be caused by overuse of the Achilles tendon,
acetaminophen A nonaspirin pain reliever or overly tight calf muscles or Achilles tendons, excess
analgesic. Acetaminophen may be given alone to uphill running, a sudden increase in the intensity of
relieve pain and inflammation or it may be com- training or the type of shoes worn to run, or wearing
bined with other drugs, as in some migraine med- high heels at work and then switching to a lower-
ications, which contain acetaminophen, a heeled workout shoe. Achilles tendonitis causes
barbiturate, and caffeine. pain, tenderness, and often swelling over the Achilles
tendon. There is pain on rising up on the toes and
acetone A volatile liquid used as an industrial pain with stretching of the tendon. The range of
solvent. Acetone is also one of the ketone bodies motion of the ankle may be limited. Treatment
that is formed when the body uses fat instead of glu- includes applying ice packs to the Achilles tendon,
cose (sugar) for energy. The formation of acetone is raising the lower leg, and taking an anti-inflamma-
usually a sign that cells lack insulin or cannot effec- tory medication. In some severe cases of Achilles
tively use the insulin that is available, as occurs in tendonitis, a cast may be needed for several weeks.
diabetes. Acetone is excreted from the body in the A heel lift insert may also be used in shoes to prevent
urine. future overstretching of the Achilles tendon. Exerting
rapid stress on the Achilles tendon when it is
acetone breath The breath of a person with inflamed can result in rupture of the tendon.
excessive acetone in their body. Acetone breath
smells fruity and is a telltale sign of significant dia- achlorhydria A lack of hydrochloric acid in the
betes. See also diabetes mellitus. digestive juices in the stomach.
acetylcholine A neurotransmitter released by achondroplasia A genetic disorder of bone
nerves that is essential for communication between growth and the most common cause of short stature
the nerves and muscles. with disproportionately short arms and legs (known
as dwarfism). The individual has a large head with
acetylsalicylic acid See aspirin. a prominent forehead (frontal bossing); underde-
velopment (hypoplasia) of the midface, with cheek-
achalasia A disease of the esophagus that mainly bones that lack prominence; and a low nasal bridge
affects young adults. Abnormal function of nerves with narrow nasal passages. The fingers are short,
and muscles of the esophagus causes difficulty swal- and the ring and middle fingers diverge to give the
lowing and sometimes chest pain. Regurgitation of hand a trident (three-pronged) appearance. The
undigested food can occur, as can coughing or brain is entirely normal in people with achon-
breathing problems related to entry of food material droplasia, but complications can damage the brain
into the lungs. The underlying problems are weak- and spinal cord. Achondroplasia is an autosomal
ness of the lower portion of the esophagus and fail- dominant trait, affecting boys and girls equally. Most
ure of the lower esophageal sphincter to open and cases are due to new gene mutations that appear for
allow passage of food. Diagnosis is made by an X- the first time in the affected child. Achondroplasia is
ray, endoscopy, or esophageal manometry. caused by mutation in the fibroblast growth factor
Treatment includes medication, dilation (stretch- receptor-3 gene (FGFR3), and prenatal diagnosis is
ing) to widen the lower part of the esophagus, and possible. See also dwarfism; dwarfism, hydro-
surgery to open the lower esophagus. A fairly recent chondroplastic.
approach involves injecting medicines into the
lower esophagus to relax the sphincter.
18. 5 acrocyanosis
acid, pantothenic Vitamin B5. See also ACOG American College of Obstetricians and
Appendix C, “Vitamins.” Gynecologists, a professional organization for
women’s health care providers that also does advo-
acid indigestion Excessive secretion of cacy work to improve the care of female patients.
hydrochloric acid by the stomach cells. Medically
known as hyperchlorhydria. Sometimes used inter- acoustic nerve The eighth cranial nerve which is
changeably with heartburn. See also heartburn. concerned with hearing, balance, and head posi-
tion. It branches into two parts—a cochlear part
acid phosphatase An enzyme that acts to liber- that transmits sound reception for hearing and a
ate phosphate under acidic conditions and is made vestibular part that senses balance and head posi-
in the liver, spleen, bone marrow, and prostate tion. Also known as the vestibulocochlear nerve.
gland. Abnormally high serum levels of acid phos-
phatase may indicate infection, injury, or cancer of acquired Not inherited, or present at birth (con-
the prostate. genital), but developing after birth. For example,
AIDS is an acquired, not an inherited, form of
acidophilus Bacteria found in yogurt with “live immune deficiency.
cultures” that can help restore supportive bacteria
to an intestinal tract whose normal bacterial popu- acquired immunodeficiency disease See
lation (flora) has been disturbed by disease or AIDS.
antibiotics. Eating yogurt with acidophilus may also
be useful in preventing overgrowth of yeast acquired mutation A genetic change that occurs
(Candida) in the intestinal tract, mouth (thrush), in a single cell after the conception of an individual.
and vagina. See also probiotic. That change is then passed along to all cells
descended from that cell. Acquired mutations are
acidosis Too much acid in the blood and body. involved in the development of cancer.
Acidosis is an abnormal condition resulting from
the accumulation of acid or the depletion of alkaline acral-lentiginous melanoma See melanoma,
reserves. The pH of a body with acidosis is below acral-lentiginous.
normal. For a person with diabetes, this can lead to
diabetic ketoacidosis. The opposite of acidosis is acrocentric chromosome A chromosome in
alkalosis. See also pH. which the centromere is located quite near one end
of the chromosome. Humans normally have five
ACL Anterior cruciate ligament. pairs of acrocentric chromosomes. Down syndrome
is caused by an extra acrocentric chromosome
acne Localized skin inflammation resulting from (chromosome 21).
overactivity of the oil glands at the base of hair folli-
cles or as a response to contact with irritating sub- acrocephalosyndactyly An inherited disorder
stances. See also acne vulgaris. characterized by abnormalities of the skull, face,
hands, and feet. It begins with premature closure of
acne rosacea See rosacea. some sutures of the skull (craniosynostosis) and
results in a tall peaked head, shallow eye sockets,
acne vulgaris The common form of acne, in and underdeveloped cheekbones. With acro-
teens and young adults, that is due to overactivity of cephalosyndactyly, fingers and toes are fused (syn-
the oil (sebaceous) glands in the skin that become dactyly), and the thumbs and big toes have broad
plugged and inflamed. Acne typically develops when ends. Acrocephalosyndactyly is an autosomal domi-
the oil glands come to life around puberty and are nant trait that affects boys and girls. A parent can
stimulated by male hormones that are produced in transmit the gene for the disorder, or it can occur
the adrenal glands of both boys and girls. due to a new mutation. Surgery is often useful to
Treatments include keeping the skin clean and correct the abnormalities of the skull, face, hands,
avoiding irritating soaps, foods, drinks, and cosmet- and feet. See also Apert syndrome; Crouzon
ics. Severe acne and acne in those who are prone to syndrome.
scarring can be treated with topical creams and oral
medications. Skin damaged by acne can be acrochordon See skin tag.
improved with treatment by a dermatologist or
facial technologist using dermabrasion (sanding), acrocyanosis Blueness of the hands and feet,
removal of scar tissue via laser, and chemical peels. usually due to inadequate circulation.
Also known as pimples.
19. acrodermatitis enteropathica 6
acrodermatitis enteropathica A progressive, active euthanasia The active acceleration of a
hereditary disease of children, characterized by the terminally ill patient’s death by use of drugs or other
simultaneous occurrence of skin inflammation means. Currently, active euthanasia is openly prac-
(dermatitis) and diarrhea. The skin on the cheeks, ticed in the Netherlands and in the US state of
elbows, and knees is inflamed, as is tissue about the Oregon. The patient’s request to the physician must
mouth and anus. There is also balding of the scalp, be voluntary, explicit, and carefully considered, and
eyebrows, and lashes; delayed wound healing; and it must be made repeatedly. Moreover, the patient’s
recurrent bacterial and fungal infections due to suffering must be unbearable and without any
immune deficiency. The key laboratory finding is an prospect of improvement. Suicide for other rea-
abnormally low blood zinc level, reflecting impaired sons, whether irrational or rational, is not active
zinc uptake. Treatment with zinc by mouth is cura- euthanasia. The forced killing of an ill or disabled
tive. Acrodermatitis enteropathica is an autosomal person, as has occurred in eugenics programs, is
recessive disorder. See also deficiency, zinc; zinc. also not active euthanasia. And although medica-
tions administered for pain relief may hasten death,
acromegaly See gigantism, pituitary. aggressive pain relief is a normal medical decision
in terminal care, not in active euthanasia. See also
acromioclavicular joint A gliding joint located assisted suicide; eugenics; euthanasia.
between the acromion (a projection of the scapula
that forms the point of the shoulder) and the clavi- active immunity Immunity produced by the
cle (the collar bone). It is served and supported by body in response to stimulation by a disease-caus-
the capsular, superior, and inferior acromioclavicu- ing organism or other agent.
lar ligaments; the articular disk; and the coraco-
clavicular (trapezoid and conoid) ligaments. activities of daily living Things that a person
Abbreviated AC joint. normally does during a day, including self-care
(eating, bathing, dressing, grooming), work, home-
acrosyndactyly A condition in which a person making, and leisure. The ability or inability to per-
has fused or webbed fingers or toes. Acrosyndactyly form these activities can be used as a practical
can be partial or complete, and it can usually be measure of ability or disability, and it may be used
corrected via surgery. It is associated with several by insurers and HMOs as a rationale for approving
birth defect syndromes. See also Apert syndrome. or denying physical therapy or other treatments.
Abbreviated ADL.
ACS American College of Surgeons, a professional
organization that administers standards of practice acuity, auditory The clearness of hearing, a
for surgeons. Those who meet the group’s standards measure of how well a person hears.
can call themselves Fellows of the ACS.
acuity, visual The clearness of vision, a measure
actinic Referring to the ultraviolet (UV) rays from of how well one sees.
sunlight and UV lamps. Sunburn is an actinic burn.
An actinic keratosis is a skin lesion that is the con- acuity test, visual The familiar eye chart test,
sequence of chronic sun exposure. which measures how well a person can see at vari-
ous distances.
actinic keratosis Rough, scaly patches of skin
that are considered precancerous and are due to acupressure The application of pressure on spe-
sun exposure. Prevention is to cut sun exposure and cific points on the body to control symptoms such
wear sunscreen. Treatments include performing as pain or nausea. Similar in concept to acupunc-
cryosurgery (freezing with liquid nitrogen), cutting ture, but without needles. See also acupuncture.
the keratoses away, burning them, putting 5-fluo-
rouracil on them, and using photodynamic therapy acupuncture The practice of inserting needles
(injecting into the bloodstream a chemical that col- into specific points on the body with a therapeutic
lects in actinic keratoses and makes them more sen- aim, such as to reduce pain or to induce anesthesia
sitive to destruction by a specialized form of light). without the use of drugs. Traditional Chinese
Also known as solar keratosis and senile keratosis. acupuncturists say the practice unblocks the flow of
a life force called ch’i; Western researchers believe
activated charcoal Charcoal that has been acupuncture may affect production of endorphins,
heated to increase its ability to absorb molecules. the body’s natural painkillers. In 1997, the National
Activated charcoal is used to help relieve intestinal Institutes of Health (NIH) issued a consensus state-
gas. It is also used to filter and purify liquids, to ment stating that “There is sufficient evidence of
absorb poisons (as in gas mask filters), and in emer- acupuncture’s value to expand its use into conven-
gency situations to neutralize swallowed poisons. tional medicine.” See also acupressure.
20. 7 acute myocardial infarction
acupuncturist A person skilled in the practice of treated, progresses quickly. In acute leukemia, the
acupuncture, who may or may not be credentialed leukemic cells are not able to mature properly.
by an accrediting body.
acute membranous gingivitis A progressive
acute Of short duration, rapid, and abbreviated in and painful infection of the mouth and throat due to
onset. A condition is termed acute in comparison to the spread of infection from the gums. Symptoms
a subacute condition, which lasts longer or changes include ulceration, swelling, and sloughing off of
less rapidly; or a chronic condition, which may last dead tissue from the mouth and throat. Certain
almost indefinitely, with virtually no change. Each germs (including fusiform bacteria and spiro-
disease has a unique time scale: An acute myocar- chetes) have been thought to be involved, but the
dial infarction (heart attack) may last a week, actual cause is not yet known. Like most other
whereas an acute sore throat may last only a day or poorly understood diseases, acute membranous
two. See also chronic. gingivitis goes by many other names, including
acute necrotizing ulcerative gingivitis, fusospirillary
acute abdomen Medical shorthand for the acute gingivitis, fusospirillosis, fusospirochetal gingivitis,
onset of abdominal pain. A potential medical emer- necrotizing gingivitis, phagedenic gingivitis, trench
gency, an acute abdomen may reflect a major prob- mouth, ulcerative gingivitis, ulcerative stomatitis,
lem with one of the organs in the abdomen, such as Vincent angina, Vincent gingivitis, Vincent infection,
appendicitis (inflamed appendix), cholecystitis and Vincent stomatitis.
(inflamed gallbladder), a perforated ulcer in the
intestine, or a ruptured spleen. acute mountain sickness The physical effect of
being in a high-altitude environment. Abbreviated
acute esophageal stricture See esophageal AMS, it is common at altitudes above 2,440
stricture, acute. meters (approximately 8,000 feet). Three-fourths of
people have mild symptoms of AMS at altitudes over
acute fatty liver of pregnancy Abbreviated 3,048 meters (approximately 10,000 feet).
AFLP, liver failure in late pregnancy, usually of Occurrence depends on the altitude, rate of ascent,
unknown cause. Symptoms include nausea and and individual susceptibility. Symptoms begin 12 to
vomiting, abdominal pain, yellowing of the skin and 24 hours after arrival at a new altitude and include
eyes (jaundice), frequent thirst (polydipsia), headache, dizziness, fatigue, shortness of breath,
increased urination (polyuria), headache, and loss of appetite, nausea, disturbed sleep, and gen-
altered mental state. Laboratory features of AFLP eral malaise. These symptoms tend to worsen at
include low blood sugar (hypoglycemia), elevated night, when the respiratory drive is decreased.
liver enzymes, and low levels of blood platelets. Symptoms should subside within 2 to 4 days,
Untreated AFLP can cause complete liver failure, and can be treated by using pain medications such
bleeding due to impaired blood clotting, and death as aspirin. Acetazolamide (brand name: Diamox)
of the mother and fetus. AFLP is treated by deliver- can also be used to minimize symptoms and may be
ing the baby as soon as possible, often by inducing taken as a preventive measure. Moderate AMS has
early labor. It usually subsides after delivery and the same symptoms as AMS, but the headaches can-
does not occur in subsequent pregnancies. In some not be relieved with medication, and both breathing
cases AFLP is associated with an abnormality of and coordinated movements become difficult. The
fatty-acid metabolism: a deficiency of the enzyme only remedies are advanced medications and
long-chain-3-hydroxyacyl-CoA dehydrogenease descent to lower altitudes. Severe AMS causes great
(LCHAD). The mother and father have half the nor- shortness of breath at rest, inability to walk,
mal LCHAD activity, and the fetus has no LCHAD decreased mental status, and fluid buildup in the
activity. This metabolic disease in the baby’s liver lungs. Severe AMS requires immediate descent to
causes the fatty liver disease in the mother. lower altitudes: 610 to 1,220 meters (approxi-
mately 2,000 to 4,000 feet). See also acclimati-
acute HIV infection See HIV infection, acute. zation to altitude.
acute idiopathic polyneuritis See Guillain- acute myelogenous leukemia See leukemia,
Barre syndrome. acute myeloid.
acute illness A disease with an abrupt onset and, acute myeloid leukemia See leukemia, acute
usually, a short course. myeloid.
acute leukemia Cancer of the blood cells that acute myocardial infarction A heart attack that
characteristically comes on suddenly and, if not occurs when the heart muscle is suddenly deprived
21. acute nonlymphocytic leukemia 8
of circulating blood. Abbreviated AMI. See also ad- Prefix indicating toward or in the direction of.
heart attack. For example, adduction is the movement of a limb
toward the midline of the body, and adrenal literally
acute nonlymphocytic leukemia See means “toward the kidney.”
leukemia, acute myeloid.
ad lib Abbreviation of the Latin phrase ad libi-
acute otitis media Painful inflammation of the tum, meaning “as much as one desires” or “at your
middle ear, typically with fluid in the middle ear, discretion.” See also Appendix A, “Prescription
behind a bulging eardrum or a perforated eardrum, Abbreviations.”
often with drainage of pus. The customary treatment
is antibiotics for 7 to 10 days. After antibiotic treat- ADA 1 American Dental Association, a professional
ment, some children are left with fluid in the middle organization for dentists. Its Council on Dental
ear, which can cause temporary hearing loss. In Education and Commission on Dental Accreditation
most children, the fluid eventually disappears spon- are responsible for accrediting schools of dentistry
taneously. If a child has a bulging eardrum and is and allied professions. 2 American Diabetes
experiencing severe pain, a myringotomy (surgical Association, a nonprofit health organization that
incision of the eardrum) to release the pus may be sponsors diabetes research, provides information
done. Tubes may be placed in the ear to drain fluid. about diabetes and diabetes prevention to patients
See also ear infection. and others, and advocates for improved treatment of
people with diabetes. 3 Adenosine deaminase.
acute peritonitis See peritonitis, acute.
Adam’s apple The familiar feature on the front of
acute respiratory distress syndrome the neck that is the forward protrusion of the thy-
Respiratory failure of sudden onset due to fluid in roid cartilage, the largest cartilage of the larynx. It
the lungs (pulmonary edema), following an abrupt tends to enlarge at adolescence, particularly in
increase in the permeability of the normal barrier males. It is usually said to take its name from the
between the capillaries in the lungs and the air sacs. extrabiblical story that a piece of the forbidden fruit
The muscles used in breathing are forced to work stuck in Adam’s throat.
harder, causing labored and inefficient breathing.
An abnormally low level of oxygen in the blood ADD 1 Attention deficit disorder. 2 Adenosine
(hypoxemia) occurs. The types of acute lung injury deaminase deficiency.
that may lead to ARDS include, but are not limited
to, aspiration of food or other items into the lungs, addiction An uncontrollable craving, seeking,
inhalation of a toxic substance, widespread infec- and use of a substance such as alcohol or another
tion of the lungs, blood infection (sepsis), and near- drug. Dependence is such an issue with addiction
drowning. Treatment frequently involves temporary that stopping is very difficult and causes severe
use of a mechanical ventilator to help the patient physical and mental reactions.
breathe.
Addison’s anemia See anemia, pernicious.
acute thrombocytopenic purpura Sudden
onset of low blood platelet levels, with bleeding into Addison’s disease Chronic underfunction of the
the skin and elsewhere. Abbreviated ATP. ATP can outer portion of the adrenal gland, most commonly
have many causes; for example, it can be a poten- due to autoimmune destruction. Other causes
tially serious complication during the acute phase of include physical trauma to the adrenal gland, hem-
measles infection. orrhage, tuberculosis, and destruction of the pitu-
itary gland cells that secrete adrenocorticotropic
acute-phase protein A protein whose plasma hormone (ACTH), which normally controls the
concentrations increase during certain inflamma- adrenal gland. Addison’s disease is characterized by
tory disorders. Perhaps the best-known acute-phase bronzing of the skin, anemia, weakness, and low
protein is C-reactive protein (CRP). blood pressure.
acyclovir A potent antiviral drug or medication adducted thumbs Clasped thumbs, caused by
(brand name: Zovirax) that works against several absence of the extensor pollicis longus and/or bre-
human herpes viruses, Epstein-Barr virus, herpes vis muscles to the thumb. When associated with
zoster, varicella (chickenpox), cytomegalovirus, mental retardation, it is part of an X-linked syn-
and other viruses. It is part of the AIDS drug AZT. drome that affects mainly boys. See MASA syn-
See also AZT. drome.
22. 9 adjuvant
adduction Movement of a limb toward the mid- first successful gene therapy for this condition in
line of the body. The opposite of adduction is abduc- humans was done in 1990, by infusing patients with
tion. genetically engineered blood cells.
adductor muscle See muscle, adductor. adenosine triphosphate A nucleotide com-
pound that is of critical importance for the storage
adenine A nucleotide member of the base pair of energy within cells and the synthesis of RNA.
adenine-thymine (A-T) in DNA. Abbreviated ATP.
adenitis Inflammation of a gland. adenovirus One of a group of viruses that can
cause infections of the lung, stomach, intestine, and
adenocarcinoma A cancer that develops in the eyes. Symptoms resemble those of the common
lining or inner surface of an organ and usually has cold. There are no effective medications for treating
glandular (secretory) properties. More than 95 per- adenovirus infection. Adenovirus infection typically
cent of prostate cancers are adenocarcinomas. does not cause death or permanent problems. More
than 40 types of adenoviruses have been recog-
adenoid A mass of lymphoid tissue in the upper nized, all of which are extremely tiny. Adenoviruses
part of the throat, behind the nose. When the ade- are being used in research as a vehicle for gene
noids are enlarged due to frequent infections, therapy and as a vector for vaccines.
breathing through the nose may become difficult.
Surgical removal may be done, often accompanied ADH Antidiuretic hormone.
by removal of the tonsils. Also known as pharyngeal
tonsil. ADH secretion, inappropriate A condition that
results in the inability to produce dilute urine and
adenoidectomy The surgical removal of the ade- imbalance of fluids and electrolytes in the body, par-
noids. ticularly lowering blood sodium. Symptoms include
nausea, vomiting, muscle cramps, confusion, and
adenoiditis Infection of the adenoids. convulsions. This syndrome may occur with oat-cell
lung cancer, pancreatic cancer, prostate cancer, and
adenoma A benign tumor that arises in or resem- Hodgkin’s disease, among other disorders. Also
bles glandular tissue. If an adenoma becomes can- known as syndrome of inappropriate ADH secretion
cerous, it is called an adenocarcinoma. or SIADH.
adenomyoma A nodule that forms around ADHD Attention deficit hyperactivity disorder.
endometrial tissue in cases of adenomyosis. See
adenomyosis. adhesion The union of two opposing tissue sur-
faces. This term is often used to refer to the sides of
adenomyosis A common, benign condition of a wound, as well as to scar tissue strands that can
the uterus in which the endometrium (the inner form at the site of a previous operation, such as
uterus) grows into the adjacent myometrium (the within the abdomen after a laparotomy.
uterine musculature located just outside the
endometrium). The myometrium may respond to adhesive capsulitis A condition in which a per-
this intrusion with muscular overgrowth. If an son has constant severe limitation of the range of
island of endometrial tissue is contained within the motion of the shoulder due to scarring around the
myometrium, it forms an adenomyoma. Also known shoulder joint. Adhesive capsulitis is an unwanted
as endometriosis interna, endometriosis uterina, consequence of rotator cuff disease that involves
adenomyosis uteri, and adenomyometritis. damage to the rotator cuff. The affected joint is
characteristically painful and tender to palpation.
adenopathy Large or swollen lymph nodes. Physical therapy and cortisone injections are often
Lymph nodes can become enlarged as a result of helpful. Surgery is used in advanced cases. Also
inflammatory diseases, infection, or cancer. known as frozen shoulder.
Synonymous with lymphadenopathy.
adipose Fatty. Adipose refers to tissue made up of
adenosine deaminase An enzyme that plays a mainly fat cells such as the yellow layer of fat
key role in salvaging purine molecules. Abbreviated beneath the skin.
ADA.
adiposis dolorosa See Dercum disease.
adenosine deaminase deficiency An autoso-
mal recessive genetic condition that results in adjuvant A substance that helps and enhances
severe combined immunodeficiency disease. The the effect of a drug, treatment, or biologic system.
23. adjuvant chemotherapy 10
adjuvant chemotherapy Chemotherapy given directives include the living will, power of attorney,
after removal of a cancerous tumor to further help and health care proxy. See also DNR.
in treatment. Many chemotherapy drugs are most
effective after the majority of the tumor has been adverse event In pharmacology, any unexpected
removed. or dangerous reaction to a drug or vaccine.
ADLs Activities of daily living. AED See automated external defibrillator.
admitting physician The doctor responsible for aer-, aero- Prefix indicating air or gas, such as
admitting a patient to a hospital or other inpatient aerogastria (excess stomach gas).
health facility.
aerobic Oxygen-requiring. Aerobic bacteria need
adnexa In gynecology, the appendages of the oxygen to grow. Aerobic exercise requires the heart
uterus, namely the ovaries, the Fallopian tubes, and and lungs to work harder to meet the body’s
the ligaments that hold the uterus in place. increased oxygen demand.
adrenal gland A small gland located on top of aerobic exercise Brisk exercise that promotes
the kidney. The adrenal glands produce hormones the circulation of oxygen through the blood and is
that help control heart rate, blood pressure, the way associated with an increased rate of breathing.
the body uses food, the levels of minerals such as Examples include running, swimming, and bicy-
sodium and potassium in the blood, and other func- cling.
tions particularly involved in stress reactions.
aerophagia Literally, eating air, from the Greek
adrenal medulla See medulla, adrenal. words aer, meaning “air,” and phagein, meaning
“to eat.” Aerophagia is a common cause of stomach
adrenaline A stress hormone produced within gas. Everyone swallows small amounts of air when
the adrenal gland that quickens the heart beat, eating or drinking. However, activities such as rapid
strengthens the force of the heart’s contraction, and eating or drinking, gum chewing, smoking, and
opens up the bronchioles in the lungs, among other wearing ill-fitting dentures may cause a significant
effects. The secretion of adrenaline is part of the increase in swallowed air.
human “fight or flight” response to fear, panic, or
perceived threat. Also known as epinephrine. aerosinusitis Painful sinus troubles due to
changing atmospheric pressures. Aerosinusitis is
adult hemoglobin See hemoglobin A. the cause of sinus pain when going up or down in a
plane. Also known as barosinusitis and sinus baro-
adult-onset diabetes Non-insulin-dependent, trauma.
or type 2, diabetes, the most common form of dia-
betes mellitus. Unlike patients with insulin-depend- aerosol A fine spray or mist. Medications in
ent, or type 1, diabetes, in whom the pancreas makes aerosol form can be administered via a nebulizer
no insulin, patients with adult-onset diabetes produce and inhaled.
some insulin, sometimes even large amounts.
However, their bodies do not produce enough insulin aerotitis Middle ear problems due to changing
or their body cells are resistant to the action of atmospheric pressures, as when a plane descends
insulin. People with this form of diabetes are fre- to land. Symptoms include ear pain, ringing ears,
quently overweight and can sometimes control their diminished hearing and, sometimes, dizziness. Also
disease by losing weight through diet and exercise. known as aerotitis media, barotitis, barotitis media,
Otherwise, they may need to combine insulin or and otic barotrauma.
another diabetes medication with diet and exercise.
See also diabetes, type 1. Aesculapius The ancient Roman god of medi-
cine, whose staff with a snake curled around it is
adult-onset Still’s disease Still’s disease that commonly used as a symbol of medicine. According
begins in adulthood rather than in childhood. See to mythology, Aesculapius’s children included
also Still’s disease. Hygeia, the goddess of health, and Panaceia, the
goddess of healing.
advance directive A document drawn up by a
patient or, in some cases, the patient’s representa- affective disorder A psychiatric disorder that
tive to set treatment preferences and to designate a affects the control of mood. See bipolar disorder;
surrogate decision maker should the patient cyclothymia; depression; seasonal affective dis-
become unable to make medical decisions. Advance order.
24. 11 Aicardis syndrome
afferent Carrying toward. A vein is an afferent ageusia An inability to taste sweet, sour, bitter, or
vessel because it carries blood from the body salty substances. People who can taste sweet, sour,
toward the heart. The opposite of afferent is effer- bitter, or salty substances but have a reduced ability
ent. to do so are said to have hypogeusia.
afferent nerve A nerve that carries impulses aggressive 1 In cancer medicine, quickly grow-
toward the central nervous system. ing or tending to spread rapidly. For example, an
aggressive tumor. 2 In psychiatry, having a ten-
afferent vessel A vessel that carries blood dency to aggression or belligerent behavior.
toward the heart. A vein or venule.
aggressive fibromatosis See desmoid tumor.
AFLP Acute fatty liver of pregnancy.
agnosia An inability to recognize sensory inputs
AFO Ankle-foot orthosis. such as light, sound, and touch). Agnosia is typically
a result of brain injury. For example, damaging the
AFP Alpha-fetoprotein. back part of the brain can cause visual agnosia
(inability to properly recognize objects by sight).
African tapeworm See Taenia saginata.
agonist A substance that acts like another sub-
African tick typhus See typhus, African tick. stance and therefore stimulates an action. Agonist is
the opposite of antagonist. Antagonists and agonists
afterbirth The placenta and the fetal membranes are key players in the chemistry of the human body
that are normally expelled from the uterus after the and in pharmacology.
birth of a baby. See also placenta.
agoraphobia An abnormal and persistent fear of
aftercare Medical care and instructions for public places or open areas, especially those from
patients after leaving a medical facility. which escape could be difficult or in which help
might not be immediately accessible. Persons with
agammaglobulinemia Total or near-total
absence of infection-fighting antibodies belonging agoraphobia frequently also have panic disorder.
to the class called gamma globulins. People with mild agoraphobia often live normal
Agammaglobulinemia can be due to certain genetic lives by avoiding anxiety-provoking situations. In the
diseases or caused by acquired diseases, including most severe agoraphobia, the victims may be inca-
AIDS. pacitated and homebound. Agoraphobia tends to
start in the mid to late 20s, and the onset may
agenesis Lack of development. For example, age- appear to be triggered by a traumatic event.
nesis of a toe means the toe failed to form. agranulocytosis A marked decrease in the num-
agenesis, sacral See caudal regression syn- ber of granulocytes (neutrophils). Agranulocytosis
drome. results in frequent chronic bacterial infections of
the skin, lungs, throat, and other areas. It can be an
agenesis of the gallbladder A condition in inherited genetic condition or acquired as, for
which the gallbladder fails to develop. It occurs in 1 example, in leukemia. See also agranulocytosis,
in about every 1,000 people, usually without addi- infantile genetic; granulocytopenia; severe con-
tional birth defects. genital neutropenia.
agent, antihypertensive See antihypertensive. agranulocytosis, infantile genetic An inherited
condition characterized by a lack of granulocytes
agent, anti-infective See anti-infective. (neutrophils), a type of white blood cell that is impor-
tant in fighting infection, and a predisposition to fre-
Agent Orange An herbicide and defoliant con- quent bacterial infections. Also known as Kostmann
taining 2,4-D and 2,4,5-T, as well as trace disease or syndrome and genetic infantile agranulocy-
amounts of dioxin. Agent Orange was used as a tosis. See also agranulocytosis; granulocytopenia;
defoliant in the Vietnam War. There has been con- severe congenital neutropenia.
cern about Agent Orange potentially causing cancer
and birth defects. agreement, arbitration See arbitration agree-
ment.
age-related macular degeneration See mac-
ular degeneration. Aicardis syndrome A rare genetic disorder that
occurs only in females and is caused by congenital
25. AID 12
absence of the corpus callosum, a large bundle of longer breathing (apneic). Loss of consciousness
nerves that connects the left and right sides of the occurs if the obstruction is not relieved. Treatment
brain. Features include epilepsy that emerges in of airway obstruction due to a foreign body includes
infancy and is difficult to control, vision problems due the Heimlich maneuver for adults, a series of five
to maldeveloped retinas, developmental delay, and abdominal thrusts for children over 1 year of age,
sometimes physical deformities of the spine, face, and a combination of five back blows with the flat of
and/or heart. See also epilepsy; seizure disorders. the hand and five abdominal thrusts with two fingers
on the upper abdomen for infants.
AID Artificial insemination by donor.
AKA Above-the-knee amputation, generally per-
AIDS Acquired immunodeficiency syndrome, a formed when the leg is not medically viable or to
syndrome caused by infection with the human prevent the spread of disease to the tissues above
immunodeficiency virus (HIV), with ensuing com- the knee from below.
promise of the body’s immune system. Features
include deficiency of certain types of leukocytes, akathisia A movement disorder characterized by
especially T cells; infection with opportunistic infec- a feeling of inner restlessness and a compelling
tions that take advantage of the impaired immune need to be in constant motion, as well as by actions
response, such as tuberculosis, bacterial pneumo- such as rocking while standing or sitting, lifting the
nia, human herpes virus, or toxoplasmosis; certain feet as if marching on the spot, and crossing and
types of cancer, particularly Kaposi sarcoma; inabil- uncrossing the legs while sitting. People with
ity to maintain body weight (wasting); and in akathisia are unable to sit or keep still, complain of
advanced cases, AIDS dementia complex. Treatment restlessness, fidget, rock from foot to foot, and
for AIDS has advanced rapidly. Antiviral, antibacter- pace.
ial, and immune-boosting medications, among other
treatments, are part of current treatment protocols. akinesia The state of being without movement.
AIDS dementia complex A brain disorder in akinetic Related to the loss of the normal ability
people with severe AIDS, causing loss of thinking to move the muscles.
capacity and affecting the ability to function. AIDS
dementia complex is considered an AIDS-defining akinetic epilepsy See epilepsy, akinetic.
illness—that is, one of the serious illnesses that
occurs in HIV-positive individuals warranting an akinetic mutism See mutism, akinetic.
AIDS diagnosis, according to the definition of AIDS
by the Centers for Disease Control and Prevention alanine aminotransferase An enzyme normally
(CDC). present in liver, skeletal muscle, and heart cells.
Abbreviated ALT. ALT is released into blood when the
AIDS-related complex A term used in the early liver, skeletal muscle, or heart is inflamed or
years of the AIDS epidemic to describe people with injured by diseases, conditions, or medications.
HIV infection who had only mild symptoms of illness, Also known as serum glutamic pyruvic transami-
such as swollen lymph glands. It is rarely used today. nase (SGPT).
Abbreviated ARC.
albinism A pigmentation disorder characterized
airway The path that air follows to get into and by partial or total lack of the pigment melanin in the
out of the lungs. The mouth and nose are the nor- skin, hair, and iris. Albinism is caused by an auto-
mal entry and exit ports for the airway. Entering air somal recessive gene and can occur in people of
then passes through the back of the throat (phar- any ethnic background. People with albinism have
ynx) and continues through the voice box (larynx), delicate skin that sunburns and develops skin can-
down the trachea, to finally pass through the cer easily, and they may suffer from eye disorders.
bronchi. See also Hermansky-Pudlak syndrome; vitiligo.
airway obstruction Partial or complete block- albino A person with albinism. The term was first
age of the breathing passages to the lungs. Causes applied by the Portuguese to people in West Africa,
include the presence of foreign matter, allergic who may have had partial or complete albinism.
reactions, infections, anatomical abnormalities, and
trauma. Associated respiratory distress may be sud- albuginea Tough white fibrous tissue. The tunica
den, with only a cough for a warning. There is often albuginea of the testis, for example, is the layer of
agitation in the early stages. Other signs include dense whitish inelastic tissue that surrounds the
labored, ineffective breathing, until the person is no testis.
26. 13 allergic conjunctivitis
albumin The main protein in human blood and on the brain, liver, and other organs of the body,
the key to regulating the osmotic pressure of blood. some of which can lead to death.
Chemically, albumin is soluble in water, precipitated
by acid, and coagulated by heat. aldosterone A hormone produced by the outer
portion (cortex) of the adrenal gland. Aldosterone
albuminuria More than the normal amount of regulates the balance of water and electrolytes in the
albumin in the urine. Albuminuria can be a sign that body, encouraging the kidney to excrete potassium
protein is leaking through the kidney, most often into the urine and retain sodium, thereby retaining
through the glomeruli, or a sign of significant kid- water. It is classified as a mineralocorticoid hor-
ney disease. It may also be the harmless result of mone.
vigorous exercise. Also known as proteinuria.
aldosteronism See Conn syndrome.
alcohol An organic substance formed when a
hydroxyl group is substituted for a hydrogen atom in alexia Loss of the ability to read or understand
a hydrocarbon. The type of alcohol used in alco- the written word, due either to brain damage that
holic beverages, ethanol, derives from fermenting disconnects these functions or to temporary dys-
sugar with yeast. After alcohol is ingested, the body function caused by abnormal electrical or chemical
converts it to sugar-based fuel. Alcohol acts as a activity in the brain.
central nervous system depressant, and it may be
part of solutions used as preservatives, antiseptics, alienist French term for a psychologist, a psychi-
or medications. atrist, or another practitioner who cares for the
mentally ill.
alcohol abuse Use of alcoholic beverages to
excess, either on individual occasions (binge drink- alimentary Concerning food, nourishment, and
ing) or as a regular practice. For some individu- the organs of digestion. From the Latin alimentum,
als—children or pregnant women, for meaning nourishment.
example—almost any amount of alcohol use may
be legally considered “alcohol abuse.” Heavy alco- alkaline phosphatase An enzyme that liberates
hol abuse can cause physical damage and death. phosphate under alkaline conditions and is made in
liver, bone, and other tissues. Alkaline phosphatase
alcohol poisoning A condition in which a toxic can be measured in a routine blood test.
amount of alcohol has been consumed, usually in a Abnormally high serum levels of alkaline phos-
short period of time. The affected individual may phatase may indicate bone disease, liver disease, or
become extremely disoriented, unresponsive, or bile duct obstruction.
unconscious, with shallow breathing. Because alco-
hol poisoning can be deadly, emergency treatment is alkalosis Relatively too much base in the blood
necessary. and body, an abnormal condition resulting from the
accumulation of base or the depletion of acid. The
alcohol use in pregnancy The consumption of pH of an alkalotic body measures above normal.
alcohol during pregnancy, which can damage the The opposite of alkalosis is acidosis.
fetus. See also fetal alcohol effect; fetal alcohol
syndrome. alkaptonuria A genetic metabolic disorder due
to deficiency of the enzyme homogentisic acid
Alcoholics Anonymous A free self-help organi- (HGA) dioxygenase. Deficiency of this enzyme leads
zation founded to assist people addicted to alcohol to the three cardinal features of alkaptonuria (the
in breaking old behavior patterns and gaining sup- presence of homogentisic acid in the urine),
port for consistently living a sober lifestyle. ochronosis (bluish-black pigmentation in connec-
tive tissue), and arthritis. Urine that turns dark is a
alcoholism Physical dependence on alcohol to characteristic feature.
the extent that stopping alcohol use would bring on
withdrawal symptoms. In popular and therapeutic allele An alternative form of a gene.
parlance, the term may also be used to refer to
ingrained drinking habits that cause health or social allergen A substance that can cause an allergic
problems. Treatment requires first ending the phys- reaction. Common allergens include ragweed
ical dependence and then making lifestyle changes pollen, animal dander, and mold.
that help the individual avoid relapse. In some
cases, medication and hospitalization are necessary. allergic conjunctivitis Inflammation of the
Alcohol dependence can have many serious effects whites of the eyes (conjunctivae), with itching, red-
ness, and tearing, due to allergy.
