This document discusses thyrotoxicosis and hyperthyroidism. It begins by covering thyroid physiology including iodine metabolism and thyroid hormone synthesis. It then discusses the causes and clinical manifestations of Graves' disease (diffuse toxic goiter), toxic multinodular goiter, and toxic adenoma. Diagnostic tests and treatment options including antithyroid drugs, radioactive iodine therapy, and surgery are described for hyperthyroidism. Thyroid storm, a medical emergency, is also summarized.

1. Thyrotoxicosis
Dr.P.Viswakumar M.S
Assistant professor,
Dept of General Surgery,
PSGIMSR

2. Thyroid Physiology
Iodine Metabolism:
• The average daily iodine requirement is 0.1 mg.
• Sources : Fish, milk, and eggs or as additives in
bread or salt.
• In the stomach and jejunum, iodine is rapidly
converted to iodide and absorbed into the
bloodstream.
• Iodide is actively transported into the thyroid
follicular cells by an adenosine triphosphate (ATP)–
dependent process.
• The thyroid is the storage site of >90% of the
body's iodine content

3. Thyroid Hormone synthesis
1) Iodide trapping, involves active (ATP-dependent)
transport of iodide across the basement
membrane of the thyrocyte via an intrinsic
membrane protein, the sodium/iodine (Na+/I–)
symporter.
2) Oxidation of iodide to iodine and iodination of
tyrosine residues on Tg, to form
monoiodotyrosines (MIT) and diiodotyrosines
(DIT).
3) Coupling of two DIT molecules to form tetra-
iodothyronine or thyroxine (T4 ), and one DIT
molecule with one MIT molecule to form 3,5,3'-
triiodothyronine (T3).

4. Thyroid Hormone synthesis
• Tg is hydrolyzed to release free iodothyronines
(T3 and T4) and mono- and diiodotyrosines by
stimulation of TSH and engulfing within
thyroid follicle.
• The latter are deiodinated in the fifth step to
yield iodide, which is reused in the thyrocyte.

8. • In the euthyroid state, T4 is produced and
released entirely by the thyroid gland,
whereas only 20% of the total T3 is produced
by the thyroid.
• Most of the T3 is produced by peripheral
deiodination (removal of 5'-iodine from the
outer ring) of T4 in the liver, muscles, kidney,
and anterior pituitary, a reaction that is
catalyzed by 5'-mono-deiodinase.
• Thyroid hormones are transported in serum
bound to carrier proteins such as T4-binding
globulin, T4-binding prealbumin, and albumin.

10. • Only a small fraction (0.02%) of thyroid
hormone (T3 and T4) is free (unbound) and
is the physiologically active component.
• T3 is the more potent of the two thyroid
hormones, although its circulating plasma
level is much lower than that of T4.
• T3 is three to four times more active than
T4 per unit weight, with a half-life of
about 1 day, compared to approximately 7
days for T4.

11. Hypothalamic-pituitary-thyroid
hormone axis

12. • The thyroid gland also is capable of
autoregulation, which allows it to modify its
function independent of TSH.
• As an adaptation to low iodide intake, the gland
preferentially synthesizes T3 rather than T4 ,
thereby increasing the efficiency of secreted
hormone.
• In situations of iodine excess, iodide transport,
peroxide generation, and synthesis and secretion
of thyroid hormones is inhibited.
• Excessively large doses of iodide may lead to
initial increased organification, followed by
suppression, a phenomenon called the Wolff-
Chaikoff effect.

13. Thyroid Hormone Function
• In humans, two types of T3 receptor genes (alpha
and beta) are located on chromosomes 3 and 17.
• Alpha form is abundant in the central nervous
system, whereas the beta form predominates in
the liver.
• Thyroid hormones affect almost every system in
the body. They are important for fetal brain
development and skeletal maturation.
• T3 increases oxygen consumption, basal metabolic
rate, and heat production by stimulation of Na+/K+
ATPase in various tissues

14. Thyroid Hormone Function
• It also has positive inotropic and chronotropic
effects on the heart(actions of catecholamines
are amplified).
• They also increase GI motility, leading to
diarrhea in hyperthyroidism and constipation
in hypothyroidism.
• Thyroid hormones also increase bone and
protein turnover and the speed of muscle
contraction and relaxation.

15. Tests of Thyroid Function
Serum Thyroid-Stimulating Hormone (Normal 0.5–5
U/mL): Serum TSH levels reflect the ability of the
anterior pituitary to detect free T4 levels. Small
changes in free T4 lead to a large shift in TSH levels
(Inverse relation).
Total T4 (Reference Range 55–150 nmol/L) and T3
(Reference Range 1.5–3.5 nmol/L).
Free T4 (Reference Range 12–28 pmol/L) and Free T3
(3–9 pmol/L).
Thyroid Antibodies : Thyroid antibodies include anti-
Tg, antimicrosomal, or anti-TPO and thyroid-
stimulating immunoglobulin (TSI).

16. Thyrotoxicosis
Hyperthyroidism

17. Thyrotoxicosis
• Biochemical and physiological
manifestation of Excessive thyroid
hormone.
• Thyrotoxicosis need not be due to
hyperthyroidism
• But hyperthyroidism mostly produce
thyrotoxicosis.

18. Hyperthyroidism
• It is a term reserved for disorder that
result in over production of hormone
by the thyroid gland.
• In short hyperthyroidism the
pathology is in the thyroid gland
itself

19. Hyperthyroidism and thyrotoxicosis
No Hyperthyroidism Toxicosis without
hyperthyroidism
1, Grave’s disease Subacute thyroiditis
2, Toxic nodular goitre Ectopic functioning thyroid
3, Toxic adenoma Silent thyroiditis
4, Jod – Basedow’s
disease
Struma ovarii
5, Metastatic follicular
carcinoma
6, Trophoblastic tumours
7, Postpartum thyroiditis
8, Thyrotoxicosis factitia

20. Diffuse toxic goitre(Grave’s disease)
• This disorder is known as Graves' disease after
Robert Graves, an Irish physician who described
three patients in 1835.
• It is an autoimmune disease with a strong familial
predisposition, female preponderance (5:1).
• Peak incidence between the ages of 40 to 60
years.
• Graves' disease is characterized by thyrotoxicosis,
diffuse goiter, and extrathyroidal conditions
including ophthalmopathy, dermopathy (pretibial
myxedema), thyroid acropachy, gynecomastia, and
other manifestations.

22. Etiology, Pathogenesis, and Pathology
• The exact etiology of the initiation of the
autoimmune process in Graves' disease is not
known.
• Postpartum state, iodine excess, lithium
therapy, and bacterial and viral infections have
been suggested as possible triggers.
• Genetic factors also play a role-HLA-B8 and
HLA-DR3 and HLADQA1*0501.

23. Etiology, Pathogenesis, and Pathology
• Stimulate B lymphocytes, which produce
antibodies directed against the thyroid hormone
receptor.
• TSIs or antibodies that stimulate the TSH-R, as
well as TSH-binding inhibiting immunoglobulins or
antibodies have been described.
• The thyroid-stimulating antibodies stimulate the
thyrocytes to grow and synthesize excess thyroid
hormone, which is a hallmark of Graves' disease.
• Graves' disease also is associated with other
autoimmune conditions such as type I diabetes
mellitus, Addison's disease, pernicious anemia,
and myasthenia gravis.

24. Etiology, Pathogenesis, and Pathology

25. Etiology, Pathogenesis, and Pathology
• Macroscopically, the thyroid gland in patients
with Graves' disease is diffusely and smoothly
enlarged, with a concomitant increase in
vascularity.
• Microscopically, the gland is hyperplastic, and the
epithelium is columnar with minimal colloid
present.
• The nuclei exhibit mitosis, and papillary
projections of hyperplastic epithelium are
common.

26. Clinical manifestation
• Divided into those related to hyperthyroidism
and those specific to Graves' disease.
• Hyperthyroid symptoms
-Heat intolerance
-Increased sweating and thirst
-Weight loss despite adequate caloric
intake

27. Clinical manifestation
• Symptoms of increased adrenergic stimulation
-palpitations, nervousness, fatigue,
emotional lability, hyperkinesis, and
tremors.
• The most common GI symptoms include increased
frequency of bowel movements and diarrhea.
• Female patients often develop amenorrhea,
decreased fertility, and an increased incidence of
miscarriages.
• Children experience rapid growth with early bone
maturation.
• Older patients may present with cardiovascular
complications such as atrial fibrillation and
congestive heart failure.

28. Other manifestation of Grave’s
• Approximately 50% of patients with Graves'
disease also develop clinically evident
ophthalmopathy, and dermopathy occurs in 1 to
2% of patients.
• Eye signs - lid lag (von Graefe's sign), spasm of the
upper eyelid revealing the sclera above the
corneoscleral limbus (Dalrymple's sign), and a
prominent stare, due to catecholamine excess.
• True infiltrative eye disease results in periorbital
edema, conjunctival swelling and congestion
(chemosis), proptosis, limitation of upward and
lateral gaze (from involvement of the inferior and
medial rectus muscles, respectively), keratitis, and
even blindness due to optic nerve involvement.

29. • Rare bony involvement leads to subperiosteal
bone formation and swelling in the
metacarpals (thyroid acropachy).
• Onycholysis, or separation of fingernails from
their beds, is a more commonly observed
finding.

31. Clinical signs
• Weight loss and facial flushing may be evident.
• The skin is warm and moist and African American
patients often note darkening of their skin.
• Tachycardia or atrial fibrillation is present with
cutaneous vasodilation leading to a widening of the
pulse pressure and a rapid falloff in the transmitted
pulse wave (collapsing pulse).
• A fine tremor, muscle wasting, and proximal muscle
group weakness with hyperactive tendon reflexes often
are present.
• The thyroid usually is diffusely and symmetrically
enlarged, as evidenced by an enlarged pyramidal lobe.
• Overlying bruit or thrill and loud venous hum in the
supraclavicular space

35. Diagnostic Tests
• Suppressed TSH with or without an elevated free T4 or
T3 level.
• If eye signs are present, other tests are generally not
needed.
• In the absence of eye findings, an 123I uptake and scan
should be performed.
• An elevated uptake, with a diffusely enlarged gland,
confirms the diagnosis of Graves' disease
• It helps to differentiate it from other causes of
hyperthyroidism.
• Anti-Tg and anti-TPO antibodies are elevated in up to
75% of patients.
• Elevated TSH-R or thyroid-stimulating antibodies (TSAb)
are diagnostic of Graves' disease and are increased in
about 90% of patients

36. Management
• Graves' disease may be treated by any of
three treatment modalities—
- Antithyroid drugs
- Thyroid ablation with radioactive 131I
- Thyroidectomy

37. Anti Thyroid Drugs
• Antithyroid medications generally are administered
in preparation for RAI ablation or surgery.
• The drugs commonly used are propylthiouracil
(PTU, 100 to 300 mg three times daily) and
methimazole (10 to 30 mg three times daily, then
once daily).
• Both drugs reduce thyroid hormone production by
inhibiting the organic binding of iodine and the
coupling of iodotyrosines (mediated by TPO).
• PTU also inhibits the peripheral conversion of T4 to
T3, making it useful for the treatment of thyroid
storm.
• PTU has a lower risk of transplacental transfer.

38. Anti Thyroid Drugs
• Side effects of treatment include reversible
granulocytopenia, skin rashes, fever,
peripheral neuritis, polyarteritis, vasculitis,
and, rarely, agranulocytosis and aplastic
anemia.
• The catecholamine response of thyrotoxicosis
can be alleviated by administering beta-
blocking agents.
• Propranolol is the most commonly prescribed
medication in doses of about 20 to 40 mg four
times daily.

39. Radioactive Iodine Therapy (131I)

40. Radioactive Iodine Therapy (131I)
• RAI forms the mainstay of Graves' disease treatment in
North America.
• The major advantages of this treatment are the
avoidance of a surgical procedure and its concomitant
risks.
• The 131I dose is calculated after a preliminary scan, and
usually consists of 8 to 12 mCi administered orally.
• After standard treatment with RAI, most patients
become euthyroid within 2 months.
• However, only about 50% of patients treated with RAI
are euthyroid 6 months after treatment, and the
remaining are still hyperthyroid or already hypothyroid

41. Radioactive Iodine Therapy (131I)
• RAI therapy is therefore most often used in older
patients with small or moderate-sized goiters,
those who have relapsed after medical or surgical
therapy.
• Contraindication :
Absolute : Women who are pregnant or
breastfeeding.
Relative : Young patients (i.e., especially children
and adolescents), those with thyroid
nodules, and those with
ophthalmopathy.

42. Surgical Treatment
• Surgery is recommended when RAI is
contraindicated
(a) Have confirmed cancer or suspicious
thyroid nodules.
(b) Young.
(c) Pregnant or desire to conceive soon
after treatment.
(d) Severe reactions to antithyroid medications
(e) Large goiters causing compressive
symptoms.
(f) Reluctant to undergo RAI therapy.

43. Surgical Treatment
• What surgical Procedure ?
1) Near total thyroidectomy
2) Subtotal thyroidectomy
3) Total thyroidectomy
4) Hartley- Dunhill procedure
- Solely based on discretion of surgeon and their
experience.

44. Toxic MNG

45. Toxic MNG
• Toxic multinodular goiters usually occur in older
individuals, who often have a prior history of a
nontoxic multinodular goiter.
• Over several years, enough thyroid nodules
become autonomous to cause hyperthyroidism.
• Hyperthyroidism also can be precipitated by
iodide-containing drugs such as contrast media and
the antiarrhythmic agent amiodarone (jodbasedow
hyperthyroidism).
• Symptoms and signs of hyperthyroidism are similar
to Graves' disease, but extrathyroidal
manifestations are absent.

46. Toxic MNG
• Blood tests are similar to Graves' disease with
a suppressed TSH level and elevated free T4 or
T3 levels.
• RAI uptake also is increased, showing multiple
nodules with increased uptake and
suppression of the remaining gland.
• Treatment – After adequately controlling
hyperthyroid state total thyroidectomy is
treatment of choice.

47. Toxic Adenoma (Plummer's Disease)
• Hyperthyroidism from a single hyperfunctioning nodule
typically occurs in younger patients who note recent
growth of a long-standing nodule along with the
symptoms of hyperthyroidism.
• Most hyperfunctioning or autonomous thyroid nodules
have attained a size of at least 3 cm before
hyperthyroidism occurs.
• Physical examination usually reveals a solitary thyroid
nodule without palpable thyroid tissue on the
contralateral side.
• RAI scanning shows a "hot" nodule with suppression
the rest of the thyroid gland. These nodules are rarely
malignant.
• Surgery (lobectomy and isthmusectomy) is preferred to
treat young patients and those with larger nodules.

48. Thyroid Storm
• Thyroid storm is a condition of hyperthyroidism
accompanied by fever, central nervous system agitation or
depression, cardiovascular dysfunction that may be
precipitated by infection, surgery, or trauma.
• Beta blockers are given to reduce peripheral T4 to T3
conversion and decrease the hyperthyroid symptoms.
• Oxygen supplementation and hemodynamic support
should be instituted.
• Non-aspirin compounds can be used to treat pyrexia and
Lugol's iodine or sodium ipodate (intravenously) should
be administered to decrease iodine uptake and thyroid
hormone secretion.
• PTU therapy blocks the formation of new thyroid
hormone and reduces peripheral conversion of T4 to T3.
• Corticosteroids often are helpful to prevent adrenal
exhaustion and block hepatic thyroid hormone
conversion.

50. Steps of Thyroidectomy

57. Thank you for your
patient listening.Hope you will
handle our hyperness with care.
Yours lovingly,
Thyroid gland.