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
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
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)
24.
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