General Medicine

Iodine Effects

• High dose, short period → Inhibits T4 synthesis (Wolff-Chaikoff effect)
• Low dose, long period → Increases T4 synthesis (Jod-Basedow effect)

Drugs Inhibiting T4→T3 Conversion

Propranolol, Dexamethasone, Propylthiouracil, High-dose iodine, Radiographic contrast

Hypothyroidism

• Best test: Raised TSH (primary hypothyroidism)
• Causes: Amyloidosis, Sarcoidosis, Hemochromatosis, Scleroderma, Cystinosis
• Drugs: Amiodarone, Lithium
• Hashimoto thyroiditis