Transient thyrotoxicosis associated with infarction of a large thyroid adenoma

We report a 46-year-old male patient with a transient thyrotoxicosis that seems to have been caused by hemorrhagic infarction of a cold thyroid nodule. The serum level of triiodothyronine was markedly but transiently elevated, while the serum thyroxine level remained within the normal range. The resected nodule, measuring 8 x 7 x 5 cm, showed extensive degeneration and necrosis with viable follicles left only at the margin of the nodule. A transient thyrotoxicosis due to acute hemorrhagic infarction of autonomously functioning thyroid nodules has already been reported. This case showed that the phenomenon could occur even in cold thyroid nodules. Its implications were discussed in relation to the high incidence of impaired TSH response to TRH in patients with nodular goiter.