Pituitary hyperthyroidism. Case report and review of the literature.

A 58 year old woman with an enlarged sella turcica was found to have hyperthyroidism with a supranormal concentration of serum thyrotropin. Transsphenoidal microsurgery resulted in the removal of a chromophobe adenoma comprised mainly of thyrotropes. Postoperatively, serum thyrotropin, thyroxine and triiodothyronine levels fell within normal limits, and the patient maintained normal thyroid and pituitary function.