To find out if sperm count is normalized in men using hCG plus TRT, several studies have found that 17OH-P blood level is correlated to intratesticular testosterone (ITT) required for the testicles to make sperm, so testing for this hormone could not only save time while optimizing HCG dose/frequency but also eliminate the need to perform testicular aspirations, a very difficult procedure to do. Sperm count does not stabilize until 6-8 weeks after starting hCG plus TRT, so knowing your 17OH-progesterone blood level can give you a quick way to determine if your hCG dose and frequency is adequate before your first follow-up semen analysis after 8 weeks.