A 34-year-old woman from Mumbai presents with a 3-month history of palpitations, tremor, and heat intolerance. She reports recent weight loss despite good appetite. On examination, she has a diffuse goitre, exophthalmos, and pretibial myxoedema. TSH is <0.01 mIU/L, free T4 is 28 pg/mL (normal 7.5–21), and free T3 is 8.5 pg/mL (normal 2.3–4.2). TPO antibodies are positive. What is the most appropriate initial pharmacological management?

Explanation

## Clinical Diagnosis **Key Point:** The combination of diffuse goitre, exophthalmos, and pretibial myxoedema is pathognomonic for Graves' disease (autoimmune hyperthyroidism). The elevated free T3 and T4 with suppressed TSH and positive TPO antibodies confirm the diagnosis. ## Rationale for Initial Management **High-Yield:** Graves' disease requires a two-pronged approach in the acute phase: 1. **Symptomatic control** — β-blocker to manage adrenergic manifestations (palpitations, tremor, heat intolerance) 2. **Thyroid hormone synthesis inhibition** — antithyroid drug (PTU or methimazole) **Clinical Pearl:** Propylthiouracil (PTU) is preferred over methimazole in the first trimester of pregnancy and in thyroid storm due to its additional benefit of inhibiting peripheral conversion of T4 → T3. However, in non-pregnant patients, methimazole is often preferred due to lower hepatotoxicity risk. In this case, PTU is chosen because it offers dual benefit: blocks synthesis AND peripheral conversion. **Key Point:** Propranolol is the β-blocker of choice (not atenolol or metoprolol) because it also inhibits peripheral conversion of T4 to T3, providing additional thyroid hormone control. ## Why NOT the Other Options | Option | Why Wrong | |--------|----------| | Levothyroxine + prednisolone | Levothyroxine is contraindicated in active hyperthyroidism; it would worsen the condition. Prednisolone is not first-line unless thyroid storm or severe eye disease. | | Methimazole alone | Monotherapy without β-blocker leaves adrenergic symptoms uncontrolled; patient remains symptomatic and at risk of arrhythmias. | | Lugol's iodine + atenolol | Iodine alone (without prior antithyroid cover) can precipitate thyroid storm by increasing hormone release. Atenolol does not inhibit peripheral T4→T3 conversion like propranolol does. | ## Treatment Timeline ```mermaid flowchart TD A[Graves' disease diagnosed]:::outcome --> B[Acute phase: PTU + Propranolol]:::action B --> C{Response in 6-8 weeks?}:::decision C -->|Yes| D[Continue PTU, taper propranolol]:::action C -->|No| E[Consider higher PTU dose or add iodine]:::action D --> F{Remission at 12-18 months?}:::decision F -->|Yes| G[Stop PTU, monitor TSH]:::outcome F -->|No| H[Radioiodine or thyroidectomy]:::action ``` **Tip:** Remember the mnemonic **"PPP"** — **P**ropranolol + **P**ropylthiouracil + **P**eriodic monitoring = first-line Graves' management.