EFFECT OF GROWTH HORMONE (GH) ON GONADOTROPIN CONCENTRATIONS IN ADOLESCENT KALES WITH GROWTH HORMONE DEFICIENCY: A PRELIMINARY REPORT

Abstract

The in vivo and in vitro effects of GH on the gonads are well known, but there are scant data about their possible influence on gonadotropin secretion. We studied five male patients with idiopathic growth hormone deficiency, 14.8 - 18.7 years of age, all of them with normal spontaneous adult pubertal development. They were studied in two opportunities: A) under GH treatment (0.5 IU/Kg/week), B) after discontinuing GH treatment. Blood samples were drawn every 20 minutes during the night for LH and FSH measurements. After the 12 hour sampling period was completed, a sample for testosterone was drawn. LH, FSH and testosterone were measured by RIA and LH was also measured by IFMA. The detection limits for LH and FSH (RIA) were 1.0 IU/L, and 0.02 IU/L for LH (IFMA). CLUSTER program was used for the analysis of spontaneous gonadotropin concentrations. Results showed that there were no differences in the levels of testosterone, LH and FSH measured by RIA, between the periods with or without GH treatment. In addition, there were no differences in the mean LH levels, the mean peak amplitude and frequency measured by IFMA, but the area under the curve and the average of nadir points were significantly lower during GH treatment (p< 0.025 and p< 0.04 respectively). These preliminary data suggest a role of GH on the regulation of LH secretion in growth hormone deficient patients, although the site at which this regulation may be exerted is not known.