Serum 17-hydroxyprogesterone strongly correlates with intratesticular testosterone in gonadotropin-suppressed normal men receiving various dosages of human chorionic gonadotropin

ObjectiveTo determine if serum concentrations of testosterone precursors would correlate with intratesticular testosterone (ITT) concentration measured directly by testicular aspiration and allow for a less invasive means of inferring ITT.DesignControlled clinical study.SettingHealthy volunteers in an academic research environment.Patient(s)Twenty-nine normal men.Intervention(s)We determined ITT concentration by testicular aspiration before and after treatment in men receiving exogenous T to block endogenous gonadotropin production and randomly assigned to one of four doses of hCG (0, 125 IU, 250 IU, or 500 IU every other day) for 3 weeks.Main Outcome Measure(s)The association between serum 17-hydroxyprogesterone (17OH-P), androstenedione, and DHEA and ITT.Result(s)With T administration alone, serum 17OH-P decreased significantly and increased significantly when 500 IU hCG was administered. End-of-treatment ITT strongly correlated with serum 17OH-P. Moreover, serum 17OH-P, but not androstenedione or DHEA, was independently associated with end-of-treatment ITT by multivariate linear regression.Conclusion(s)Serum 17OH-P is highly correlated with ITT in gonadotropin-suppressed normal men receiving T and stimulated with hCG. Serum 17OH-P is a surrogate biomarker of ITT and may be useful in research and in men receiving gonadotropin therapy for infertility.