[Analysis of luteinizing hormone pulses in men with idiopathic hypogonadotropic hypogonadism]

In order to test the defect of luteinizing hormone (LH) pulses and its relationship with sexual development in patients with idiopathic hypogonadotropic hypogonadism (IHH), fourteen male IHH patients and five healthy adult men were investigated. Blood samples were withdrawn at 10 minute intervals for 24h for analysis of LH pulse. LH pulse frequency ranged from 0-13 pulses/24h. Testosterone (T) level was 1.3-8.7 nmol/L in the 14 IHH patients and higher in the 5 healthy controls (all P < 0.01). Two of the patients with IHH had no detectable LH pulsations (apulsatile pattern), no history of puberty and a small testicular volume of less than 1ml. Most of the IHH patients (n = 9) had less pulse frequency (4-13 pulses/24h) and lower mean amplitude (1.3-2.2IU/L) than the healthy controls (14-20 pulses/24h and 3.81-2.46IU/L, P < 0.01). A patient with IHH had 10 pulses/24h and more or less the same mean amplitude (4.2 +/- 1IU/L) as the healthy controls; his T level was the lowest among the 14 patients due probably to biological inactivity of LH. Two IHH patients had detectable LH pulsations with normal mean amplitude (P > 0.05) present predominantly during the night, this pattern of LH pulse resembles that of peripuberty boy. Our results indicate that (1) LH pulse pattern varies widely among IHH patients and it is related to the sex characteristics; (2) frequency of LH pulses is essential for sexual development. but adequate amplitude is more important in this respect.