Recurrent gestational transient thyrotoxicosis presenting as hyperemesis.

A 28-year-old G2P1 Thai woman presented with severe nausea and vomiting at 12 weeks' gestation. The initial diagnosis was hyperemesis gravidarum. She was clinically euthyroid. Physical examination revealed no thyroid gland enlargement. The serum thyroid stimulating hormone was suppressed while the free thyroxine level was elevated. This patient had a history of hyperthyroidism during her first pregnancy. An anti-thyroid drug was initiated at 16 weeks' gestation and continued throughout her pregnancy. Follow-up thyroid function tests and thyroid antibodies after her first and second gestation were normal. The diagnosis of recurrent gestational thyrotoxicosis was established. There was no need of antithyroid drug treatment in this case. No adverse pregnancy outcomes were reported.