TESTICULAR ACTIVITY IN CUSHING'S DISEASE

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Abstract
Plasma testosterone levels were suppressed in 6 of 8 mature male patients with Crushing''s disease, all of whom complained of loss of libido and decreased sexual potency. Gonadotropin levels, both under basal conditions and in response to LH-RH [luliberin], were generally normal. The testicular response to stimulation with hCG [human chorionic gonadotropin] was brisk in the 2 patients examined. Estradiol [E2] levels were slightly elevated in 2 patients and prolactin [PRL] levels were normal in all patients. Thus, male patients with Cushing''s disease demonstrated normal gonadotropin levels in the presence of suppressed testosterone, [T] or, viewed from a slightly different prospect, low T levels despite normal gonadotrophins. Neither E2 nor PRL excess appeared to account for the observations. Possible explanations for these findings include a combination of impaired hypothalamic and testicular function, and a resetting downwards of the level of T that is seen as appropriate by the disordered hypothalamic-pituitary unit. Following correction of cortisol excess in Cushing''s disease, testosterone levels rose into the normal range.