THE EFFECT OF GONADOTROPHIN RELEASING HORMONE ON PITUITARY-GONADAL FUNCTION IN KLINEFELTER'S SYNDROME

Abstract

The mean basal plasma LH [luteinizing hormone] and FSH [follicle stimulating hormone] levels in 8 patients with Klinefelter''s syndrome were, respectively, 5 and 15-fold higher than in 8 eugonadal males, whereas plasma testosterone concentration were half the normal value. After an i.v. bolus injection of gonadotropin releasing hormone (100 .mu.g of LH-RH), the gonadotropin increase in the Klinefelter patients was more marked than in the control subjects, but in both groups the plasma testosterone levels remained essentially unchanged. In contrast to the bolus injection, an 8 h infusion of LH-RH after the bolus elicited a significant plasma testosterone increase in the eugonadal males (59%) and the Klinefelter patients (51%). Despite an impressive endogenous hypergonadotrophism, Leydig cells in Klinefelter''s syndrome may still respond to a sustained further increase of these endogenous gonadotropins and still have a functional reserve.