This is a single-marker test measuring total testosterone. It can be ordered as part of a custom panel.
Testosterone is a steroid hormone that circulates around the body in the blood.
A testosterone levels test measures the amount of testosterone in a blood sample. Testosterone is known as a "male" sex hormone, but females have testosterone in smaller amounts.
In men, testosterone is produced by the testicles and the adrenal gland, controlling the production of sperm and male sex characteristics.
In women, testosterone is produced by the ovaries, the adrenal gland, and other tissues and is involved in overall growth and development.
Testosterone production is controlled by the luteinizing hormone (LH). Testosterone works within a negative feedback loop, so as testosterone levels rise, LH decreases, while increased LH causes decreased testosterone.
Testosterone levels peak in the early morning hours and have the lowest levels in the evening. Levels increase after exercise and decrease with age.
Total testosterone test: is the sum of all the testosterone in the blood, bound or not. This is the most common type of test.
Free testosterone test: measures the "active" form of hormone floating in the blood freely without being attached to any molecule. This test is less common but may help diagnose specific medical conditions. High-free testosterone in women and men can impact both health and behavior.
Bioavailable testosterone test: measures free testosterone and testosterone that's loosely attached to a blood protein called albumin. This test isn't commonly done. But, like a free testosterone test, it may help diagnose certain medical conditions.
A physician may order the testosterone test if:
Testosterone levels can be checked in children and teens to find out what's causing:
This is a single-marker test measuring total testosterone. It can be used to evaluate androgen excess or deficiency related to gonadal function, adrenal function, or tumor activity.