TSH-Secreting Pituitary Adenomas

Pituitary thyrotropin-producing adenomas (TSHomas) are rare cause of secondary hyperthyroidism, a condition characterized by the chronic stimulation of an intrinsically normal thyroid gland. These tumors account for less than 2% of all pituitary adenomas, and their recognition has been facilitated by the introduction in the clinical routine of ultrasensitive TSH immunometric assays as well as by the direct measurement of circulating free T4 and free T3.