This document discusses hypothyroidism and hyperthyroidism. It defines primary and secondary hypothyroidism, and lists common causes such as iodine deficiency, autoimmune diseases, drugs, and radiation therapy. Signs and symptoms of hypothyroidism are described. Diagnosis involves measuring TSH and free T4 levels. Treatment is typically levothyroxine, with monitoring of medication levels and watch for complications like myxedema coma. Hyperthyroidism is also covered, defining overt and subclinical presentations. Common causes include Graves' disease, multinodular goiter, and thyroiditis. Signs, evaluations involving thyroid hormone levels, and treatments are summarized.

1. Dr Parag Yadav

3. Hypothyroidism
 Presentation from asymptomatic disease to myxoedema coma.

4. Aetiology
 Primary-
Inadequate thyroid hormone from thyroid gland
 Secondary/ central-
Pathology related to pituitary or hypothalamus

5. Primary hypothyroidism-Aetiology
 Iodine deficiency
 Autoimmune thyroid diseases
 Hashimoto thyroiditis
 Drugs- Amiodarone, Tyrosine Kinase Inhibitors(TKI), Riphampin ,
Ethionamide, Phenytoin, Carbamazepine etc.
 Thyroid Radioactive Iodine Therapy
 Thyroid Surgery
 Radiotherapy to head or neck area

6. Central hypothyroidism-Aetiology
 Neoplastic, Infiltrative, Inflammatory, Genetic, Iatrogenic disorders.
 Pituitary tumours
 Tumours compressing hypothalamus
 Sheehan syndrome
 TRH resistance
 Lymphocytic hypophysitis
 Radiation therapy to the brain
 Drugs such as dopamine, prednisone, Opioids etc.

7.  Post partum thyroiditis
 Radioactive iodine in treatment of graves disease
 Sub acute granulomatous thyroiditis

8. Epidemiology
 Prevalence among adults
 More prevalence in women with small stature at birth,
Low BMI in childhood
 Female gender and increasing age associated with higher TSH and
prevalence of Antithyroid antibodies

9. Pathophysiology

10. Histopathology
 Autoimmune thyroiditis–
Increase in turnover of iodine and impaired organification
 Chronic inflammation T cell lymphocytic infiltration lymphocytic
hyperplasia dense fibrosis an atrophic follicles

11. History
 Typical-Cold intolerance, Puffiness, Decreased sweating
 Dry skin, voice change hair loss,
constipation, fatigue muscle cramps,
cold intolerance, sleep disturbance M.C. Abnormalities,
weight gain, Galactorhoea
 Depression, anxiety, psychosis, memory loss
 Rarely- Ascites, Pericardial Effusion.

12.  Carpel tunnel syndrome, Sleep apnoea,
 Hyponatremia, Hypercholesterolemia,
 Congestive Heart Failure, Prolonged QT interval
 Hashimoto disease-
Fullness of throat, fatigue, painless thyroid enlargement

13. Evaluation
 Overt hypothyroidism
TSH elevated, free T4 low
 Subclinical hypothyroidism
TSH elevated, free T4 normal
 Central hypothyroidism-
Biologically inactive TSH.
Diagnosis on free T4

14.  Autoimmune Hypo thyroiditis
 Anti thyroid antibodies- TPO antibodies
 Euthyroid sickness-
 In hospitalized patients.
 Reverse T3 elevated
 Hyperlipidaemia, elevated serum CK, elevated hepatic enzymes, anaemia,
increased BUN, creatinine, uric acid

15. Lab investigations

16. Treatment
 Levothyroxine monotherapy
 1.6 mcg/kg/day
 30-45 min before breakfast or at least 3 hrs post meal
 Proton pump inhibitors negative impact on levothyroxine absorption

17.  IV form of drug in myxedema coma
 Gel formulations- triocent- in malabsorptionsyndrome
 Sucralfate, calcium preparation, bile acid sequestrants- interfere
absorption
 Lab- every 4-8 weeks until target achieved. 6 months after stable

18.  Cardiac disease-
Monitor for angina/ A.F. Over treated for extended period of time
Osteoporosis

19. Prognosis
Failure to treat - Severe mental retardation in children
In adult- Heart failure

20. Complications
 Myxoedema coma
 Myxedema crisis-
Encephalopathy, hypothermia, seizures, hyponatremia, hypoglycaemia,
Arythmia, respiratory failure.
 Treatment-
Thyroid replacement treatment with IV hydrocortisone

21. Hyperthyroidism
 Hypothyroidism is a Syndrome associated with
excess thyroid hormone production
 Thyrotoxicosis is a state of excess thyroid hormone
exposure to tissues

22.  Overt hyperthyroidism
low TSH, elevated T3, T4
 T3 toxicosis
T3 elevated, normal T4, low TSH
 Subclinical hyperthyroidism
low TSH, normal T3 And T4

23. Etiology
 Graves disease
 Toxic Multinodular Goiter
 Toxic adenoma
 Other-
 Iodine induced
 TSH secreting pituitary adenoma
 Coditions with high HCG levels
 Ectopic thyroid in struma ovarii
 Extensive metastasis from thyroid Ca
 Drug induced Thyroiditis
 Factitious thyroiditis (excessive use of pharmaceutical thyroid hormone)

25. Pathophysiology
 Graves disease-
Autoimmune process.
Antibodies against TSH receptors  increase production and release of
thyroid hormone
 Toxic multi nodular goiter
Development of nodular disease  somatic mutation lead to activation of
cAMP pathway  Hyperthyroidism

26.  Iodine induced hyperthyroidism -
From excessive iodine intake
Excess iodide inhibit organification (iodide to thyroid conversion). This is
Wolff-chaikoff effect.
Fails in “Jod-basedow phenomenon” Excess thyroid hormone
 Amiodarone induced thyrotoxicosis
1. With pre existing thyroid diseases
2. Destructive thyroiditis due to toxic effect of amiodarone

27. Thyroiditis
 Inflammation and destruction of thyroid follicle cells
 1. Autoimmune cause
 2. external factors-infection, drug induced

28. History
 Hyperadrenergic and hypermetabolic state like symptoms
 Palpitation tremors
 Heat intolerance dyspnea on exertion
 Anxiety irritability
 Fatigue hair loss
 Oligomenorhoea/amenorhoea
 Subactue thyroiditis-
Anterior neck pain and fever
 Eye signs-Lid lag, Lid retraction
Diplopia, excessive tearing

29. EVALUATION
 Measurement of TSH, Free T4 & Total T3
 Overt hyperthyroidism -
low TSH, elevated T3, T4
 T3 toxicosis -
T3 elevated, normal T4, low TSH
 Subclinical hyperthyroidism -
low TSH, normal T3 And T4
 Heterothile antibodies – false elevation of TSH
 Biotin – high dose biotin- falsely low TSH

30.  Measurement of thyrotropin receptor antibody(TRAb) – elevated in
“Graves Disease”
 If TRAb is normal – Radio-iodine thyroid uptake
High Uptake –
1. Graves Disease – Diffuse pattern
2. TMNG – Patch pattern
3.Thyroid Adenoma- solitary area high uptake
Low uptake
1.Thyroidities
2.Iatrogenic

31. Lab investigations