Gonadotrophin release after TRH in prepubertal subjects

Abstract

In some instances, the gonadotrophins were found to be released after TRH administration in adults. Therefore, we evaluated serum gonadotrophin concentrations after separated injections of LHRH (25 μg/m2) and TRH (6 μg/kg up to 200 μg). The latter was injected 90 min after the former. The FSH and LH concentrations measured immediately before LHRH and TRH injections were considered as basal values to calculate the subsequent responses. The data were analyzed according to sex and to the prepubertal (PP) or pubertal (P) pattern of gonadotrophin responses to LHRH (JCEM, 54:733,1982). Only patients with either gonadal or hypothalamopituitary deficiency were excluded. In 9 PP boys, the mean (± SEM) FSH increment after TRH was 1.67 ± 0.67 mIU/ml. This represents 53% of the FSH response to LHRH in these subjects. In 17 P boys, a lower (P < 0.05) FSH increment after TRH was observed : 0.38 ± 0.11 mIU/ml (17% of the response to LHRH). In 16 PP girls, the mean FSH increment after TRH was 1.36 ± 0.37 mIU/ml (15% of the response to LHRH). In 5 P girls, it was only 0.24±0.15 mIU/ml (3% of the response to LHRH). In PP boys and girls, the mean LH increments after TRH represented respectively 53 and 29% of the LH responses to LHRH; in contrast, they represented 6 and 0% of the responses to LHRH in P boys and girls. Since TRH might elicit a gonadotrophin release in PP subjects, we suggest that it should be administred apart from LHRH.