Hormones & Steroids

Testosterone Testosterone is the primary male sex hormone and an anabolic steroid. In male humans, it is secreted by the testes and it plays a key role in the development of male reproductive tissues, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair. In addition, testosterone is involved in health and well-being, and the prevention of osteoporosis. Testosterone in also important in women and it is produced by the ovaries and the adrenal glands. It is best known for its role in a promoting a woman’s sex drive or libido however, it is also important for bone strength and the development of lean muscle mass. In males, a testosterone assay is used to detect hypogonadonism, testicular failure, infertility, hypopituitarism and hyperprolactinemia. In females, it can be used to diagnose polycystic ovary syndrome, adrenal hyperplasia, infertility, hirsutism, amenorrhea, obesity and virilization. Typically, a test for total testosterone is used – this test measures testosterone that is bound to proteins in the blood (e.g., albumin and sex-hormone binding globulin [SHBG]) as well as testosterone that is not bound (free testosterone). About two-thirds of testosterone circulates in the blood bound to SHBG and slightly less than one-third bound to albumin. A small percent (less than 4%) circulates as free testosterone. Free testosterone plus the testosterone bound to albumin is the bioavailable testosterone, which can act on target tissues. In many cases, the total testosterone test provides adequate information. However, in certain cases, for example when the level of SHBG is abnormal, a test for free or bioavailable testosterone may be performed as it may more accurately reflect the presence of a medical condition. Testosterone immunoassays are usually MAb-based competitive ELISAs.

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Endocrine Disorders - Reagents for Assay Development

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