anabolic steroid or androgenic steroid, any of a group of synthetic derivatives of testosterone that promote muscle and bone growth. Used to treat uncontrolled weight loss in wasting diseases, anabolic steroids have also been taken by bodybuilders and athletes seeking increased muscle mass, strength, and stamina. Such use is banned by the International Olympic Committee and other governing bodies in sports, but not all sports test for steroids. Major League Baseball did not test for steroids until 2003, when random testing returned positive results on more than 5% of the players tested, and the National Hockey League still does not test. Under a 1988 federal law it is illegal to distribute anabolic steroids for nontherapeutic uses, and in 1991 they joined other abused drugs as controlled substances. Nonetheless, a precursor hormone called dehydroepiandrosterone (DHEA), which can convert to testosterone in the body, is available as a dietary supplement without a prescription. Abuse of anabolic steroids may lead to elevated cholesterol levels, liver disease, blood clots leading to heart attack or stroke, increased aggressiveness and irritability, and, in adolescents, permanent stunting of growth. See also steroids.

Any of a class of natural or synthetic organic compounds with a molecular core, or nucleus, of 17 carbon atoms in a characteristic three-dimensional arrangement of four rings. The configuration of the nucleus, the nature of the groups attached to it, and their positions distinguish different steroids. Hundreds have been found in plants and animals and thousands more synthesized or made by modifying natural steroids. Steroids are important in biology, chemistry, and medicine. Examples include many hormones (including the sex hormones), bile acids, sterols (including cholesterol), and oral contraceptives (see contraception). Digitalis was the first steroid widely used in Western medicine. Corticosteroids (see cortisone) and their synthetic analogs are used to treat rheumatism and other inflammatory ailments. Seealso anabolic steroid.

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