Pituitary-gonadal function in the carcinoid syndrome: effect of parachlorophynylalanine therapy.

Six patients with the carcinoid syndrome (C.S) had serum luteinizing hormone (LH) concentrations that were greater than age and sex matched control subjects. The serum follicle stimulating hormone (FSH) and testosterone concentrations of the groups did not differ. Four of the 5 C.S. patients tested had an increase in serum testosterone after human chorionic gonadotropin administration and 5 of the 5 subjects tested had an increase in serum LH after clomiphene citrate administration. One of the 4 subjects treated with the tryptophan hydroxylase inhibitor parachlorophenylalanine (PCPA) had a reduction in serum testosterone. He was also receiving methysergide. The other 3 subjects treated with PCPA did not have any persistent alterations in serum testosterone.