Effect of Synthetic Luteinizing Hormone-Releasing Hormone (LH-RH) on the Release of Gonadotropins in Hypophyso-Gonadal Disorders of Children and Adolescents. III. Hypopituitarism

Abstract

The effects of synthetic luteinizing hormone-releasing hormone (LH-RH) on serum gonadotropins (LH and FSH) levels in 24 unpuberal hypopituitary patients have been compared to those observed in 25 normal prepuberal children. In control boys (n = 17) the mean level of LH rose from 1.9 ng LER 960/ml (basal) to 10 ng/ml (peak), and the mean level of FSH rose from 1.3 ng LER 1366/ml (basal) to 2.3 ng/ml (peak). In control girls (n = 8) the mean level of LH rose from 1.5 ng LER 960/ml (basal) to 4.7 ng/ml (peak), and the mean level of FSH rose from 1.1 ng LER 1366/ml (basal) to 4.5 ng/ml (peak). In 3 patients with organic hypopituitarism who failed to respond to TRH, no response to LH-RH was obtained. In 10 male patients with evidence of hypogonadotropic hypogonadism, including 3 cases with multiple deficiencies and normal response to TRH, the mean peak value of LH after LH-RH was 2.9 ng LER 960/ml, significantly lower than in controls (p ≤ 0.001). LH failed to rise in 2 patients of this group and FSH failed to rise in 6. In 11 hypopituitary subjects who demonstrated a normal response to TRH, and whose bone age below 10 yr did not allow clinical evaluation of gonadotropic secretion, the mean peak level of LH was 2.3 ng LER 960/ml, similar to the value observed in hypogonadotropic patients, and both gonadotropins failed to rise after LHRH in 2. These data indicate that the LH-RH test may be a valuable tool for the diagnosis of pituitary gonadotropic defects in children as well as in subjects having reached the bone age corresponding to onset of puberty. However, its value for determining the hypothalamic or pituitary localization of the primary defect has to be questioned. The existence of a pituitary mobilizable reserve of gonadotropins seems more dependent on endogenous releasing hormone (s) than is the reserve of thyrotropin.