Diagnosis of hypogonadotrophism versus delayed puberty in the male at pubertal age

Abstract

This differentation often appears impossible at pubertal age. In groups of boys the conditions differ in plasma testosterone response to HCG and LH response to GnRH. However, in clinically unclear individual cases the tests often fail too. We have followed 32 boys until the diagnosis of hypogonadotrophism was clinically certain. All had been given a GnRH test (3.5 μg/kg up to the maximum of 100 μg GnRH iv) and some an HCG test (5000 IU/m2 im on days 1, 3, 8 and 10, with determination of serum testosterone on days 1 and 15). We have compared their results with the results of 68 normal boys at similar, usually markedly delayed development. Every primary test parameter showed an overlap between the two groups. Best in discrimination were the logarithms of stimulated testosterone level (lnTs) and maximal increment in LH level (lnΔ LHmax). The lower limit of 90% confidence range for lnTs in the reference series detected 6/8 of the hypogonadotrophic against none of the reference boys. The same limit for lnΔLHmax detected 64% of the hypogonadotrophic boys in 47 tests against 4% of the reference boys. The product of these two parameters (lnTs × lnΔLHmax) appears superior. Data being so far available for 8 hypogonadotrophic and 17 reference boys, these groups are completely separated by the product, and with a wide margin. Further data are being collected to allow a reliable evaluation of this new diagnostic parameter.