Studies on pituitary-gonadal function in patients with Cushing's syndrome

Basal levels of sex steroids, and the responses of LH and FSH to LH-RH were studied in twenty-five female patients with Cushing's syndrome (17 Cushing's disease and 8 adrenocortical adenoma). Only two patients had a regular menstrual cycle. Amenorrhea or oligomenorrhea had been of long duration in the other cases except for three postmenopausal patients. In patients with Cushing's disease, basal estradiol was low or below normal in 86%. Progesterone was normal in 83%, but testosterone was high in half of the cases. The response of LH to LH-RH in patients with Cushing's disease was normal in 35%, low in 35% and high in 29% of the cases. FSH response to LH-RH was normal in 23.5%, low in 23.5% and high in 53%. In patients with adrenocortical adenoma, basal of estradiol was low or below normal, but progesterone and testosterone were normal in all cases. The response of LH and FSH to LH-RH in all patients with adrenocortical adenoma was higher than normal. In three postmenopausal women, a higher response of LH and FSH to LH-RH was seen in two cases and suppressed in one case. These data suggest that the main site of suppression of the gonadal axis in patients with adrenocortical adenoma is the gonad rather than the pituitary gland or hypothalamus, though the mechanism of hypogonadism in patients with Cushing's disease is heterogeneous.