A 37-year-old woman has had difficulty swallowing and a feeling of fullness in the anterior neck for the past week. She is recovering from a mild upper respiratory tract infection 1 month ago. On physical examination, her temperature is 37.4degC, pulse is 74/min, respirations are 16/min, and blood pressure is 122/80 mm Hg. Palpation of her diffusely enlarged thyroid elicits pain. Laboratory studies show an increased serum T4 level and a decreased TSH level. Two months later, she no longer has these complaints. The T4 the level is now normal. Which of the following conditions is most likely to have produced these findings?

Subacute granulomatous thyroiditis (de Quervain thyroiditis) is a self-limited condition that can be of viral origin because many cases are preceded by an upper respiratory infection. The transient hyperthyroidism results from the inflammatory destruction of the thyroid follicles and the release of thyroid hormone. The released colloid acts as a foreign body, producing florid granulomatous inflammation in the thyroid. Hashimoto thyroiditis can enlarge the thyroid transiently, but there is usually no pain or hyperthyroidism. Thyroid neoplasms are not typically associated with signs and symptoms of inflammation and are rarely functional. A toxic multinodular goiter likewise produces no signs of inflammation and does not reverse functionality.