Production rates of testosterone in patients with Cushing's syndrome

Testosterone production rates were determined in 16 patients with Gushing's syndrome (4 men and 12 women) using the stable-isotope dilution technique and mass spectrometry. 1 alpha,2 alpha-D-Testosterone was infused for 10 ho urs at a dose of 20 mu g/h (men) and 0.4 mu g/h (women) and blood samples w ere obtained at 20-minute intervals during the last 4 hours of the observat ion period. Estimated production rates in men with Gushing's syndrome were 27, 73, 150, and 180 mu g/h (mean, 106 +/- 70 mu g/h; healthy men [n = 12], 210 +/- 70 mu g/h). In the 12 women with Gushing's syndrome, testosterone production rates were 0.3 to 22.3 mu g/h (healthy women [n = 5], 4.3 +/- 1. 9 mu g/h), There was no difference in testosterone production rates in fema le patients with central (n = 8) versus adrenal (n = 4) Gushing's syndrome. In summary, testosterone production rates are subnormal or low-normal in m ale patients with endogenous hypercortisolism, but not in female patients w ith the same disorder. We conclude that testosterone production in men, but not in women, is predominantly of gonadal origin and hence susceptible to a glucocorticoid-induced suppression of gonadotropin secretion. Copyright ( C) 2000 by W.B, Saunders Company.