Clinical and laboratory heterogeneity in idiopathic hypogonadotropic hypogonadism

Six young men with idiopathic hypogonadotropic hypogonadism had 24-h frequent blood sampling studies for measurement of LH, FSH and testosterone. Five of the patients had LH and FSH measured after administration of 100 mug LH-RH during waking and then during sleep. Four of the patients had testicular biopsies performed. The results of the present studies showed that 4 of the patients had no evidence of episodic LH, FSH, or testosterone secretion. The two patients who showed significant sleep related pulses of LH had the highest 24 h mean testosterone concentrations, the best responses to exogenous LH-RH and the most differentiated testicular biopsies. Sleep had no effect on the release of LH or FSH in response to LH-RH. These sutdies suggest that the clinical and laboratory heterogeneity of idiopathic hypogonadotropic hypogonadism may be the result of differences in the degree of endogenous LH-RH deficiency.