Post-partum thyroiditis (PPT) affects 5–9% of women in the first year after delivery. Regarding its natural history and clinical management, which statement is accurate?

• A PPT is caused by postpartum surge in TSH stimulating thyroid autoimmunity
• B PPT hyperthyroid phase should be treated with propylthiouracil to prevent thyroid storm
• C PPT follows a biphasic pattern in ~30% of women: initial hyperthyroid phase (3–6 months) followed by hypothyroid phase (6–12 months) with permanent hypothyroidism in 25–30% at 3–5 years ✓
• D All women with PPT recover completely by 12 months; long-term follow-up is not required

Explanation

Post-partum thyroiditis is a destructive autoimmune thyroiditis (lymphocytic) with a classic triphasic or biphasic pattern. Approximately 30% have the biphasic pattern: destructive thyrotoxicosis (3–6 months postpartum — painless, transient) followed by hypothyroidism (6–12 months). The hyperthyroid phase is destructive (not hypersynthetic), so antithyroid drugs (PTU/carbimazole) are not effective and not indicated; β-blockers for symptoms are appropriate. The key long-term concern is that 25–30% of women with PPT develop permanent hypothyroidism by 3–5 years (higher risk with TPO antibody positivity), necessitating annual thyroid function monitoring indefinitely.

Reference: Williams Obstetrics, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.