Reversible thyrotroph hyperplasia with hyperprolactinemia: A rare presenting manifestation of primary hypothyroidism.

Pituitary thyrotroph hyperplasia with hyperprolactinemia has been described as a rare presentation of primary hypothyroidism. Premenopausal females with this disorder can present with features of hypothyroidism, menstrual disturbances, galactorrhea, and visual field defects because of enlarged pituitary. Here we describe a 32-year-old female presenting to her gynecologist primarily with galactorrhea and secondary amenorrhea. She was found to have raised serum prolactin, and MRI brain showed enlarged pituitary. She was referred for pituitary surgery when she came to us. Clinical examination and biochemistry were suggestive of primary hypothyroidism. She was prescribed levothyroxine replacement. At 6 weeks follow-up, serum prolactin came down to normal, galactorrhea subsided, and spontaneous menstrual cycles resumed. In 12 weeks, pituitary enlargement completely regressed and in another month after that, she conceived. Hence, primary hypothyroidism can present with thyrotroph hyperplasia, where correct diagnosis and levothyroxine therapy can prevent unnecessary pituitary surgery. Hyperprolactinemia in this setting is of no clinical significance.