Effects of gonadotropin and testosterone treatments on plasma leptin levels in male patients with idiopathic hypogonadotropic hypogonadism and Klinefelter's syndrome.

Since little is known about the effects of gonadotropin and testosterone treatment on leptin levels in male hypogonadism, we determined fasting plasma leptin levels before and 3 months after treatment in 21 patients with idiopathic hypogonadotropic hypogonadism (IHH), 16 patients with Klinefelter's syndrome and 20 male controls. Patients with IHH were treated with hCG/human menopausal gonadotropin, whereas patients with Klinefelter's syndrome received T treatment. Plasma leptin levels were measured by an RIA with a sensitivity of 0.5 microg/L. Mean leptin levels in patients with IHH before treatment (9.23+/-4.09 microg/L) were not significantly different from those in patients with Klinefelter's syndrome (7.29+/-5.05 microg/L; z=-1.41; P=0.15). Leptin levels in both IHH and Klinefelter's syndrome groups were, however, significantly higher than in the normal men (3.91+/-1.67 microg/L) (P<0.001 and P<0.01, respectively). Mean leptin levels did not change significantly 3 months after the initiation of gonadotropin (11.6+/-6.44 microg/L) or T (8.32+/-5.17 microg/L) treatment in either IHH or Klinefelter's syndrome. Our study demonstrated that mean plasma leptin levels are not influenced by short-term gonadotropin or T treatment in male hypogonadism.