The study design included six visits. During the first visit (visit 0), the subjects underwent physical examination(height, weight, body mass index (BMI), arm span, and upper segment measurement) and testicular ultrasound (US) for the calculation of testicular volume. At 0800 h of day 0, all subjects provided a basal blood sample immediately followed by a single intramuscular injection of hCG of 5000 IU. Further five visits were performed each of five following consecutive days after the hCG injection. A blood sample was taken at each visit after an overnight fast