To assess the efficacy of the gonadotropin-releasing hormone (GnRH) agonist buserelin in a stimulated gonadotropin test for the investigation of delayed puberty in males.

Prepubertal males (n = 31; age range, 10.3 to 17.2 years) were studied; buserelin (100 μg) was administered subcutaneously, with blood sampling at 0 and 4 hours for serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH). At follow-up (mean, 4.2 years), 8/31 (26%) failed to progress into puberty, constituting hypogonadotropic hypogonadism (HH), but 23/31 (74%) had testicular enlargement (≥8 mL) consistent with a normal hypothalamic-pituitary-gonadal (HPG) axis.

Stimulated serum LH response to buserelin was lower in males with HH (mean ± standard error under the mean for HH, 1.4 ± 0.5 U/L, compared with a normal HPG axis of 17.4 ± 2.0 U/L; P < .0001). Stimulated serum FSH response was nondiscriminatory (HH, 7.7 ± 2.2 U/L; normal HPG axis, 11.5 ± 1.6 U/L; P = .27). All males with HH had a stimulated serum LH level <5 U/L, whereas only 1/23 with a normal HPG axis had a stimulated serum LH below this level. Using this value as the criterion for diagnosing HH, the buserelin stimulation test yielded a sensitivity of 100%, specificity of 96%, and positive predictive value of 89%.

The buserelin stimulation test is a highly specific and sensitive GnRH agonist test for the investigation of males with delayed puberty.