The effect of long-term pulsatile GnRH administration on the 24-hour integrated concentration of GH in hypogonadotropic hypogonadic patients.

Measurement of integrated concentration of GH by means of continuous withdrawal sampling is a method of evaluating physiological hormonal secretion. Integrated concentration of GH was evaluated in 5 subjects with idiopathic hypogonadal hypogonadism (range 19-27 years) and in a 17-year-old male with idiopathic delay of puberty (5 males, 1 female) before and 30-240 days after the start of pulsatile GnRH administration. Gonadotropins and testosterone or 17 beta-estradiol were restored, whereas 24-h integrated concentration of GH (before therapy 5.4 +/- 1.3 IU/1; during GnRH 8.1 +/- 2.0 IU/1; P less than 0.05) was increased by GnRH therapy. However, no correlation was found between GH levels and sex steroid concentrations during GnRH pulsatile administration. These data further confirm that a physiological increase in gonadotropins and sex steroids can modulate GH synthesis and/or release.