Effect of synthetic luteinizing hormone releasing hormone (LH-RH) on the release of gonadotropins in Cushing's disease.

The effect of intravenous synthetic luteinizing hormone releasing hormone (LH-RH) on plasma radioimmunoassayable levels of gonadotropins was investigated in 6 women suffering from Cushing's disease with bilateral adrenal hyperplasia. In five of six cases no significant variation of plasma LH levels was found following stimulation; in one case the response to LH-RH was present although slightly reduced below the normal range. By contrast in all cases the plasma FSH response was similar to that recorded in normal subjects. The explanation of impaired LH response is not clear but the possibility that endogenous hypercortisolism affects the pituitary responsiveness to LH-RH has to be considered.