Hypersecretion of an abnormal form of follicle-stimulating hormone associated with suppressed luteinizing hormone secretion in a woman with a pituitary adenoma.

Pituitary tumors producing FSH have hitherto been reported only in males, all of whom have had normal or raised LH levels in serum. This report describes a female with a pituitary adenoma associated with supranormal serum levels of FSH. The FSH was also qualitatively abnormal when compared with FSH in the serum of other postmenopausal women, had a lower apparent molecular weight on gel chromatography, and was less negatively charged, as shown by electrophoresis. The results of LRH tests and suppression tests with ethinyl estradiol indicated autonomy of the FSH-producing adenoma. The FSH level increased concomitant with tumor enlargement and decreased after surgical removal of the pituitary adenoma or pituitary irradiation. The serum level of the glycoprotein alpha-subunit was raised about 100-fold. Any free FSH beta-subunits were not detectable in serum. The abnormal FSH had antigenic sites in common with both the alpha- and beta-subunits of FSH. The LH level was extremely low, and there was no response to LRH tests or ethinyl estradiol treatment. After gel chromatography, a small amount of LH, corresponding to 1/50th of the average for the patient's age, was detected at the position for normal LH. There was no GH response to insulin-induced hypoglycemia, while the cortisol increase was normal. Thyroid and adrenal functions were normal. The PRL level was within the normal range and increased slightly after estrogen treatment.