During pregnancy, how should management of hypothyroidism be adjusted?

During pregnancy, how should management of hypothyroidism be adjusted?

• A. Decrease dose by 50%
• B. Increase by about 25–30% upon pregnancy confirmation and monitor TSH and free T4
• C. No change
• D. Switch to liothyronine only

Answer: (B)

During pregnancy, maternal thyroid hormone needs rise because estrogen increases thyroid-binding globulin, placental metabolism alters hormone turnover, and the fetus relies on maternal T4 especially early on. To keep both mother and baby in a euthyroid state, the thyroid hormone replacement dose typically must be increased by about a quarter to a third once pregnancy is confirmed, with close monitoring of thyroid function tests. Checking TSH and free T4 helps guide the adjustment and ensure targets are met, usually with repeat testing every few weeks early in pregnancy. Decreasing the dose would risk hypothyroidism, not changing the dose fails to meet increased needs, and using thyroid hormone as T3-only therapy is not appropriate in pregnancy because T4 is essential for fetal development and overall maternal stability.

During pregnancy, maternal thyroid hormone needs rise because estrogen increases thyroid-binding globulin, placental metabolism alters hormone turnover, and the fetus relies on maternal T4 especially early on. To keep both mother and baby in a euthyroid state, the thyroid hormone replacement dose typically must be increased by about a quarter to a third once pregnancy is confirmed, with close monitoring of thyroid function tests. Checking TSH and free T4 helps guide the adjustment and ensure targets are met, usually with repeat testing every few weeks early in pregnancy. Decreasing the dose would risk hypothyroidism, not changing the dose fails to meet increased needs, and using thyroid hormone as T3-only therapy is not appropriate in pregnancy because T4 is essential for fetal development and overall maternal stability.