GnRH and hCG tests in healthy adolescents and adults

With the aim of obtaining reference values of GnRH test and of hCG test in a Venezuelan population, the authors evaluated the response of the pituitary LH and FSH to the GnRH action in 48 adolescents and 43 adults. Also, in 22 adolescents and in 22 adults from the same sample they evaluated the hCG effect on the gonadal steroids secretion. The maximum LH increment was obtained 30 min after GnRH stimulation, independently from the patients' age and their sexual development. FSH maximum increment was obtained 60 min after GnRH in the adults; meanwhile, the FSH maximum increment was obtained 30 min after GnRH stimulation in the Tanner stage 4 adolescents, and 90 min post-GnRH in the Tanner 5 adolescents. The gonadal steroid secretion 2, 24, 48, and 72 h post-hCG was significantly lower in the Tanner 4 adolescents. The gonadal steroid response post-hGC stimulation in the Tanner 5 adolescent group was similar to the one obtained in the adults. In late puberty the LH response to GnRH stimulus is not related either to age or to sexual development, contrary to the FSH response obtained after GnRH and the gonadal steroid response after hCG stimulus, both of which are related to age and patients' sexual development.