FSH and LH are produced by the pituitary gland to control the production of sex hormones including testosterone and estrogen, and sperm and egg cells. They are both important in diagnosing primary or secondary hypogonadism, infertility, or potential pituitary adenomas.

 Progesterone is a female hormone important for the regulation of ovulation and menstruation. It is also present in men in smaller concentrations. Progesterone is a steroid hormone that plays numerous roles within the human body. It is crucial to the production of sex hormones and corticosteroids, as well as playing a role as a neuro-steroid (brain function). 

This is the most accurate progesterone test that has no potential interactions and can detect very low levels in men and women.  Since it is performed with liquid chromatography and mass spectrometry, results are available after 5 to 7 business days.

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.