This test measures the levels of free testosterone in the serum. Testosterone is a steroid hormone (androgen) primarily produced by the testes in males, but it is also secreted in smaller amounts by the adrenal glands in both men and women, as well as by the ovaries in females.
Free testosterone refers to the fraction of the hormone that is not bound to proteins in the blood and is available to exert its effects on the body. It plays a key role in various functions, including muscle growth, bone density, libido, and mood regulation.