Testosterone

• delayed or precocious (early) puberty (boys)
• decreased sex drive (men)
• erectile dysfunction (men)
• infertility (men and women)
• excessive body hair, also called hirsutism (women)

The test may be performed if a young boy seems to be undergoing a very early (precocious) puberty with obvious secondary sex characteristics, such as an enlarged penis, development of muscle mass and growth of body hair.

In men, the test may be performed when infertility is suspected or if the patient has a decreased sex drive or erectile dysfunction, which can result from low testosterone levels.

In women, testosterone may be measured if a patient has irregular or no menstrual periods, is having difficulty getting pregnant, or appears to have masculine features, such as facial and body hair, male pattern baldness and a low voice. Testosterone levels can rise because of tumours that develop in either the ovary or adrenal gland or because of other conditions, such as polycystic ovarian syndrome (PCOS).

However, in males, a decreased testosterone level may indicate hypothalamic or pituitary disease with reduced secretion of LH and FSH, or damage to the testes with reduced production of testosterone. Genetic diseases also can cause decreased testosterone production in young men (Klinefelter’s, Kallman’s, and Prader-Willi syndromes) or testicular failure and infertility (as in myotonic dystrophy, a form of muscular dystrophy). A decreased testosterone level also can indicate impaired testosterone production because of acquired damage to the testes, such as alcoholism, physical injury or viral diseases like mumps.

Increased testosterone levels in males can indicate testicular tumours or use of androgens (also called anabolic steroids). Increased testosterone in boys is usually the cause of early puberty.

In women, increased testosterone levels can indicate polycystic ovary syndrome (PCOS) or an ovarian or adrenal gland tumour.