FSH-secreting pituitary adenomas: stimulation and suppression studies in two patients.

Two patients with pituitary adenomas, partial hypopituitarism and abnormally high serum concentrations of FSH are described. In neither patient was FSH increased after the administration of LH releasing hormone and in one patient tested, there was no FSH response to clomiphene citrate. The decrease in serum FSH in response to high concentrations of testosterone (greater than 1100 ng/dl) was less than in normal men. These results indicate partial autonomy of FSH producing adenomas. Since the elevated serum FSH produced no obvious clinical symptoms, it may be undetected unless serum FSH concentrations are measured routinely in patients with pituitary tumors.