3. Embryology
The thyroid develops at the base of the tongue
between the first pair of pharyngeal pouches
(foramen cecum)
The thyroid gland then descends
It remains connected to the floor of the
A pyramidal lobe (50–80%)
23. Physiology
The release of TH into circulation within 30 minutes of
TSH stimulation
2-3 month supply stored in colloid
In plasma:
T4(90%) and T3 (T4 5’-Deiodinase)
Free T4 (0.1%) and T3
T4 less active, longer half life (7d), T3 much more
active, shorter half life (1d)
Thyroxine binding globulin( 25% saturated)
If amount o thyroid-binding globulin (TBG)
changes, only total T4 changes, not free T4
24. Physiology
Cardiovascular system: HR, CO , blood flow, blood
volume, widened pulse pressure
Respiratory system: RR , tidal volume
Gastrointestinal system: Increased motility
Central nervous system: Temp. , Nervousness, anxiety
Musculoskeletal system: Increased reactivity up to a
point, fine motor tremor
Sleep: Constant fatigue but decreased ability to sleep
Nutrition: BMR, need or vitamins, decreased weight
25. Common Symptoms
Swelling “Goiter”
Heat or cold- intolerance
Weight loss or gain
Increased or decreased appetite
Cardiovascular and/or respiratory symptoms
Fatigue, weakness, apathy
Decreased libido, infertility
Menstrual abnormality
28. Congenital Anomalies
Persistent sinus tract remnant of developing gland
(M.C.)
Sistrunk’s operation
Complete failure to develop
Incomplete descent: Lingual or subhyoid position
May be the only functioning thyroid
Excessive descent: Substernal thyroid
Malformation of branchial pouch
32. Goiter
Inflammatory “Eu/Hypo/Hyper”:
Acute pyogenic
De Quervain's Disease
Hashimoto’s Disease
Riedel’s Fibrosing Thyroiditis
Neoplastic “Eu/Hyper”:
Primary vs Secondary “Mets, M.C RCC”
Primary: According to cell of origin
33. Goiter
Primary: According to cell of origin
Follicular:
Well differentiated:
I. Papillary
II. Follicular
III. Hurthle’s Cell
IV. Oncocytoma
Poorly differentiated:
I. Anaplastic
Parafollicular:
I. Medullary
34. Goiter
Stromal :
I. Lymphoma (confused with
Hashimoto’s thyroiditis)
Note: There are subtypes and mixed tumors
35. Goiter
Nodular goiter DDx:
Dominant nodule of MNG (50%)
Follicular adenoma (25%)
Malignancy (12.5%)
Miscellaneous (12.5)
Suspect nodule be malignant if:
Old age, male, family history, radiation history
Signs: hoarseness, pain radiating to the ear,
rapidly growing, skin ulceration, calcium
imbalance symptoms, MEN II
36. Goiter
Indications of surgery:
General: suspicion of malignancy, compression,
Follicular lesion on biopsy
Specific:
Cosmetic: Simple goiter, Thyroiditis
Failure of medical treatment: Simple goiter,
Thyroiditis, Toxic goiter
Retrosternal Thyroid: Any goiter
Exophthalmos: Toxic goiter
37. Hyperthyroidism
Definition:
Overactive thyroid, elevated level of TH (T4 and T3)
with subsequent signs and symptoms of increased
thyroid function
Primary: high T4, low TSH
Secondary: high T4, High TSH
41. Graves’ disease
Autoimmune disease caused by antibodies that activate
the TSHR on the follicular cells
Risk Factors:
Females
Age (20-25y)
Family history
Associated with Other autoimmune diseases
Diagnosis:
Thyroid function tests (high T4 and T3, Low TSH)
Radioactive iodide uptake test (RAIU)
42. Graves’ disease
Treatment:
Medical
Radioablation
Surgery
Choosing the treatment depend on the individual
case (Age, severity, size, surgical risk, treatment side
effects, comorbidities)
43. Graves’ disease
Radioablation:
Indicated for small or medium-sized goiters, if
medical therapy has failed, or if other options are
contraindicated
Euthyroid within 2 months
Most patients ultimately require TH replacement
Complications include exacerbation of thyroid storm
initially
Contraindicated in pregnant patients, women of
childbearing age and newborns
44. Graves’ disease
Surgical treatment:
Total, Subtotal, Lobar removal
Indicated when radioablation is contraindicated or if
medical management cannot be used
Patients should be euthyroid prior to excision
Advantage over radioablation is immediate cure
Complication: RLN injury, Hypoparathyroidism,
persistent hyperthyroidism, transient
hyperparathyroidism (M.C)
45. Toxic Multinodular Goiter
AKA “Plummer’s Disease”
Etiology:
Iodine deficiency
mutation in the TSH receptor
Diagnosis: Labs, Biopsy
Treatment: Best is surgical because radioablation has
high rate of failure
47. Thyroid Storm
AKA “Thyrotoxicosis”
Caused by exacerbating factors that precipitate extreme
hyperthyroidism in a hyperthyroid patient
inadequately prepared patient
Infection
Labor
iodide administration
recent radioablation
48. Thyroid Storm
Signs and Symptoms:
Fever, tachycardia, muscle stiffness or tremor,
disorientation/altered mental status
50% of patients develop CHF
Mortality rate of 20-40%
Treatment:
Best way is to AVOID it
Fluids, Anti-thyroid medication, β-blockers,
corticosteroids, sodium iodide or Lugol’s solution “KI” ,
and cooling blanket
50. Hypothyroidism
AKA: Myxedema
Definition: Underactive thyroid, low levels of T4 and
T3
Signs and Symptoms: Differ depending on age
In ants/pediatrics: Characteristic Down’s-like
faces, failure to thrive, mental retardation
Adolescents/adults:
CVS
CNS
Weight and appetite
Sexual Dysfunction
51. Hypothyroidism
Less common complaints: Yellow-tinged skin, hair loss,
tongue enlargement
Reduced Reflex Relaxation time is a pathognomonic
DDX:
Autoimmune thyroiditis
Iatrogenic: thyroidectomy, radioablation, secondary to
anti-thyroid medications
Iodine deficiency
52. Hypothyroidism
Diagnosis: by H&E and Labs
low T4 and T3
Primary VS Secondary
TRH challenge
Thyroid autoantibodies positive in autoimmune
thyroiditis
Low hematocrit (Hct.)
Treatment: PO Thyroxine
58. de Quervain’s Thyroiditis
Subacute granulomatous inflammation of the thyroid
Etiology: Post–viral upper respiratory infection
Risk actors: Female sex
Signs and symptoms: Fatigue, depression, neck pain,
ever, unilateral swelling of thyroid with overlying
erythema, firm and tender thyroid, transient
hyperthyroidism usually preceding hypothyroid phase
59. de Quervain’s Thyroiditis
Diagnosis: Made by history and exam
Treatment:
Usually self -limited disease (within 6 weeks)
Manage pain with (NSAID)
Ten percent o patients with subacute thyroiditis
become permanently hypothyroid, require
Thyroxine
61. Hashimoto’s Thyroiditis
AKA: Chronic Lymphocytic Thyroiditis
Etiology: Autoimmune
Risk actors: Down’s syndrome, Turner syndrome, familial
Alzheimer’s disease, history of radiation therapy as child
Signs and symptoms: Painless enlargement of thyroid,
neck tightness, presence of other autoimmune diseases
20% of patients with Hashimoto’s thyroiditis will be
hypothyroid at diagnosis. A euthyroid state is more
common
62. Hashimoto’s Thyroiditis
Diagnosis: Made by history, physical, and labs
Labs: Circulating antibodies against microsomal thyroid cell,
TH, T3,T4, or TSH receptor
Pathology: Firm, symmetrical, enlargement; follicular and
Hürthle cell hyperplasia; lymphocytic and plasma cell
infiltrates
Biopsy: Very similar to Hashimoto’s Thyroiditis
63. Hashimoto’s Thyroiditis
Treatment:
Thyroid hormone (usually results in regression of
goiter)
With failure o medical therapy, partial thyroidectomy is
indicated
If biopsy confirms lymphoma during surgery, there is
no need to remove the thyroid (very responsive to
chemotherapy)
68. Riedel’s Fibrosing
Thyroiditis
Rare, fibrosis replaces both lobes and isthmus
Risk actors: Associated with other fibrosing
conditions, like retroperitoneal fibrosis, sclerosing
cholangitis
Signs and symptoms: Usually remain euthyroid; neck
pain, possible airway compromise; firm, non-tender,
enlarged thyroid
Diagnosis: Open biopsy required to rule out
carcinoma or lymphoma
69. Riedel’s Fibrosing
Thyroiditis
Pathology: Dense, invasive fibrosis of both lobes and
isthmus. May also involve adjacent structures
Treatment:
With airway compromise: Isthmectomy
Without airway compromise: Medical treatment with
steroids.
76. Thyroid Cancer
MEN II A “Sipple’s Syndrome”
Medullary Thyroid cancer (100%)
20% of MTC is due to MEN II
Parathyroid hyperplasia (50%)
Pheochromocytoma (33%)
MEN II B:
Mucosal Neuroma (100%)
Medullary Thyroid Caner (85%)
Pheochromocytoma (50%)
Marfanoid Habitus
77. Thyroid Cancer
Workup of a mass:
Solitary nodule (15% malignant)
Multiple nodules (5% malignant)
90-95% are well differentiated
Start with U/S and Lab tests, if not diagnostic, FNA is used:
Benign(65%): follow on U/S and labs
Malignant(15%): Surgery
Suspicious
78. Thyroid Cancer
Suspicious/Non-diagnostic(15%): obtain 123 I Scan
85% cold nodule with 10-25% chance of malignancy
5% hot nodule with 1% chance of malignancy
Surgery if: serial T4 levels fail to regress or future biopsies are worrisome
Tumor markers:
Follicular: Thyroglobulin
Parafollicular: Calcitonin
79. Thyroid Cancer
Biopsy Findings:
Papillary: Papillary projections (M.C) Psammoma bodies, orphan Anne eye
Calcifications are seen only in papillary tumor
80. Thyroid Cancer
Biopsy Findings:
Follicular: Follicles with
capsular invasion
FNA can never
differentiate between
follicular adenoma and
carcinoma
81. Thyroid Cancer
Biopsy Findings:
Anaplastic: highly cellular
undifferentiated cells
Invade near by structures
82. Thyroid Cancer
Biopsy Findings:
Medullary: sheets of malignant
cells in an amyloid stroma
Neuroendocrine cell that
produce many types of
hormones (commonly
calcitonin)
83. Thyroid Cancer
Cancer surgery:
Papillary: thyroidectomy with LN dissection, radioablation could be done
<1.5cm: Hemithyroidectomy
>1.5cm: Total thyroidectomy
If LN positive: modified radical dissection
The other lobe may be removed prophylactically
Follicular: Thyroidectomy with radioablation of the remnant tissue
<4cm: Hemithyroidectomy
>4cm: Total thyroidectomy
If LN positive: modified radical dissection
84. Thyroid Cancer
Medullary: Total thyroidectomy with central neck LN dissection
Anaplastic: Debulking surgery for relief of compression only “Isthmectomy”
Lymphoma: Chemotherapy, no surgery
Hemithyroidectomy: Lobe removal + isthmus removal
Radioablation: Post operative thyroid hunger (at least 2wks) the diagnostic radioiodine
uptake test with (5mCi), if positive, treat with (125mCi). Repeat diagnostic test, if positive, give
(175mCi)