Aldosterone (ALD) is one of a group of connected hormones. They form the renin-angiotensin-aldosterone system; this system is activated when there is a decrease in blood flow to your kidneys following a drop in blood volume or blood pressure

Renin, also known as angiotensinogenase, is an enzyme that the kidneys produce to regulate aldosterone production. It’s also essential in the renin–angiotensin aldosterone system (RAAS) which maintains your body’s fluid balance and blood pressure. Aldosterone is the primary of several endogenous members of the class of mineralocorticoids in humans. Aldosterone tends to promote sodium and water retention, and lower plasma postasium concentrations.

This test measures levels of drenocorticotropic hormone (ACTH), which is also called adrenocorticotropin and corticotropin, a hormone made in the anterior pituitary gland that tells the adrenal glands to release cortisol, DHEA, and aldosterone. The ACTH plasma test quantifies the blood's level of ACTH. A patient's blood is drawn for the test and then sent to a lab for examination. The test findings enable the diagnosis of ailments such as Addison's disease, Cushing's syndrome, and adrenal tumors

Discounted Labs’ basic adrenal insufficiency panel includes cortisol, ACTH, and DHEA as a starting point. Depending on lab test results from this panel, physicians may choose to do an ACTH stimulation test, renin, potassium, and sodium. Imaging studies like a CT scan of the adrenal glands may also be considered to check for adrenal growths. In order to check for Addison's Disease, the auto-immune type of primary adrenal insufficiency, labs should be drawn to check 21-hydroxylase 

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.