Regression of both pituitary and ovarian cysts after administration of thyroid hormone in a case of primary hypothyroidism

We report a 19-year-old woman who was diagnosed as polycystic ovary. Hypoth yroidism with a markedly elevated TSH level and an enlarged pituitary gland on MRI were noted. The I-123 uptake was decreased to 6.5%. After treatment with thyroid hormone, regression of the enlarged pituitary and the ovarian cysts was observed. In the present case, hypothyroidism was considered to have caused a reversible enlargement of the pituitary gland and concomitant polycystic ovary. We concluded that the polycystic ovary might have result ed from the effects of an excessive amount of TSH on immature ovaries.