[Kinetics of the testicular steroidogenic response to stimulation by placental gonadotropin hormone. VI. Enzyme deficiencies of testicular biosynthesis].

The kinetics of the responses of plasma testosterone (T) its precursors and estrogens to a single injection of human chorionic gonadotropin (hCG) was studied in 9 46 XY subjects affected with one of 4 inborn errors of testicular biosynthesis. In the adults (n = 4), the kinetics and profile of the hormonal responses to hCG were qualitatively comparable to those previously described in normal adult men, and the profile of response characteristic of the hCG-induced steroidogenic desensitization was observed, suggesting that the 17,20 desmolase blockade induced by hCG is superimposed to the inborn enzymatic defect. In the prepubertal patients (n = 5), testicular desensitization was not observed, as in prepubertal controls. However, T precursors, each marker of a given enzymatic blockade, significantly rose several fold 2-5 days after the hCG injection, while they do not in normal children. The results also show that an hCG test is necessary for a clear-cut diagnosis of a given enzymatic block in children, but is not in adults. The single hCG injection protocol used in this study offers a sophisticated way of a qualitative analysis of the testicular secretory products, but is not a must.