Description
This test measures both Total and Free Testosterone and can be ordered for both men and women. For men, this test evaluates testicular function where obesity, liver or thyroid disorders may change the testosterone binding proteins. For women, this test evaluates masculinization and hirsutism (unwanted male-pattern hair growth on a woman`s face, chest, and back).Helpful in assessing testicular function in prepubescent hypogonadal males and in managing hirsutism, virilization in females.Testosterone is the main sex hormone in men and is responsible for male physical characteristics. Typically testosterone is considered to be a male sex hormone, but it is present in the blood of females as well.
This testosterone blood test measures the total amount of testosterone that is bound to proteins in the blood as well as testosterone that is not bound (free testosterone). Approximately two-thirds of testosterone circulates in the blood bound to SHBG and less than one-third is bound to albumin. A small percent (less than 4 percent) circulates in the blood as free testosterone.When testosterone levels are low, the hypothalamus secretes gonadotropin-releasing hormone (GnRH) to stimulate the anterior pituitary to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In men, FSH stimulates spermatogenesis, while LH stimulates testicular production of testosterone.
Testosterone circulates in the blood as a free, active form (less than 5%); weakly bound to albumin (approximately 30%); or tightly bound to sex hormone binding globulin (SHBG, approximately 65%).Free and albumin-bound testosterone readily enter cells, and their levels better reflect the testosterone available for use by the body. Together free testosterone and albumin-bound testosterone are called bioavailable testosterone.Bioavailable testosterone measurements are appropriate in the evaluation of females and children, as well as in males where the total testosterone levels are in the low-normal range or where abnormal SHBG levels are suspected .Hence testosterone test is done to check the abnormal testosterone levels in males and females. Testosterone levels are used to determine erectile dysfunction in men, premature and delayed puberty in men, impotence, infertility, appearance of masculine physical features in females and as an indicator for polycystic ovary syndrome (PCOS).
The test is also performed to screen for any damages or disease of ovaries, testes, adrenal or pituitary gland. For females, free testosterone levels are more important to diagnose infertility and PCOD.
