Uses. Testosterone was discovered in the 1930s. It is primarily a male hormone but is found in females as well. Various forms of testosterone exist, and body chemistry can transform them into still other substances. They play major roles in maintaining male physical characteristics: genitals and prostate, beard and other body hair, voice quality, and body build. Testosterone is suspected of influencing thinking abilities and definitely can influence behavior, such as encouraging mania and aggression. One study found high testosterone amounts in criminals with personality disorder, with repeat offenders having the highest amounts. Experimenters documented that giving high doses to mares resulted in "markedly vicious stallion-like" conduct. Low testosterone levels in men can make them tired and depressed, reduce their interest in sexual activity, and cause male physical characteristics to diminish. In contrast to high and low amounts, one study found that normal levels of testosterone in men promoted normal behavior and feelings, such as geniality and contentment.
Doses of the drug can supplement the body's natural supply of male hormones if the supply is abnormally low. Testosterone is a treatment for male sexual dysfunction. Experimental use of the drug to alleviate depression and weight loss in HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) patients has been successful. The drug has also improved liver cirrhosis and a blood disease called aplastic anemia and is used against a bone affliction called myelosclerosis. In experiments testosterone improved the condition of heart patients suffering from angina (pain caused by insufficient cardiac oxygen supply), and an experiment showed benefit for coronary artery disease patients. A case report tells of success in treating
Felty's syndrome, an affliction involving rheumatoid arthritis accompanied by abnormalities in the blood and spleen. In men testosterone is used to combat osteoporosis, a disease causing brittleness in bones. Ordinarily the drug is not given to women but is sometimes appropriate in cases of hormonal imbalance or sexual dysfunction.
Examination of fluid circulating in the human brain shows higher-than-normal levels of testosterone in smokers addicted to nicotine and lower-than-normal levels in persons suffering from posttraumatic stress disorder. Blood studies find that female smokers and overweight women have higher testosterone levels than nonsmokers or lean persons. Such discoveries have led investigators to speculate that testosterone affects those conditions. Heightened testosterone levels have also been seen in women experiencing major depression. Among men with low body levels of testosterone, supplemental doses may help reduce depression. The drug's ability to affect depression was under investigation when this book was written.
Drawbacks. Unwanted effects of testosterone dosage may include acne, headache, higher blood pressure and cholesterol levels, gastrointestinal bleeding, promotion of baldness, and enlargement of prostate and male breasts. The drug should be avoided by men with breast or prostate cancer. Liver damage is suspected. Breathing interruptions during sleep can occur. The substance may cause fluid to build up in body tissues, which can be a serious problem for persons with heart, liver, or kidney disease. A case report associated a stroke with high levels of testosterone in a 21-year-old man who was injecting himself. When administered in a skin patch the compound can cause rashes, burning sensations, and even blisters.
Normally women are supposed to avoid taking the substance. It can cause their voices to deepen, promote hair growth on various parts of the body, induce irregular menstrual periods, and bring about genital changes. Sometimes women inadvertently receive doses from residual amounts on the skin of men who are using testosterone creams or skin patches. Such inadvertent dosage can be enough to bring on some male physical characteristics in a woman (such as development of facial hair). A case study notes premature puberty that began in a child who received the same type of exposure. Another inadvertent source of testosterone is meat from livestock that has been illegally dosed. Agricultural sources of the drug are not necessarily illicit; for example, chicken litter is used for cattle feed, and chicken manure may contain testosterone excreted by the birds, thereby dosing the cattle. Even some feeds used in salmon farming contain testosterone. Human consumption of such food animals may well be safe, but they are possible dosage routes for the drug in humans if regulations about agricultural use of the substance are disregarded.
Abuse factors. If used properly testosterone can stimulate muscle development, which tempts some athletes to try the drug regardless of whether a doctor is willing to prescribe it. Such unauthorized use can have bad consequences. One bodybuilder injected the substance into his right leg, which resulted in severe muscle damage making the right leg 40% weaker than his left one. Illicit testosterone use is also suspected of reducing male fertility; indeed, the drug has been investigated as a possible male contraceptive. Taking the compound without medical supervision can be particularly risky for adolescents, as testosterone can first make a young person taller but then prematurely halt further bone growth, thereby preventing attainment of normal adult height. Still another bad consequence of an athlete's illicit usage of testosterone may occur if sports regulatory authorities discover that an athlete is using it; the drug is banned from competitions.
Drug interactions. An experiment found that eating licorice reduces testosterone levels in men, enough that the candy may contribute to problems of male sexual function. Adolescent hamsters that drink alcohol show elevated testosterone levels, and a human study showed high levels among some alcoholics. Testosterone impairs blood clotting, which may dangerously boost actions from medicines given to reduce blood clots.
Cancer. Although testosterone is a naturally occurring substance in mammals, additional doses of testosterone have caused cancer of the breast, uterus, and cervix in mice and are suspected of promoting liver cancer in mice and rats. An experiment using both testosterone and estrogen produced cancer in hamsters. Testosterone is not proven to produce cancer in humans but is under suspicion. The drug may help bring about human prostate cancer but is not necessarily a direct cause. A case of kidney cancer has been ascribed to lengthy dosage, and in other case reports, testosterone was suspected of causing liver cancer. Paradoxically the drug has been used to help treat cancer.
Pregnancy. In animal tests the drug has caused pregnancy failure and has masculinized female offspring. Human fetal harm is a suspected consequence if pregnant women take doses of testosterone. A case report said that using the drug during pregnancy caused ambiguous gender appearance in a child, an appearance so ambiguous that the child was misidentified as male for several years even though she was female (as demonstrated by assorted medical tests and by the fact that as an adult she gave birth to a child). Testosterone has been investigated as a potential drug for stopping a woman's milk production. Regarding pregnancy and nursing, one manufacturer of the drug bluntly states that the product "must not be used in women."
Additional information. In addition to testosterone itself other pharmaceutical varieties (called "esters") are testosterone cypionate, testosterone decanoate, testosterone enanthate, testosterone isocaproate, testosterone pro-pionate, and testosterone undecanoate. These are used for the same purposes that testosterone is used, and they basically have the same effects.
Additional scientific information may be found in:
Dabbs, J.M., and M.F. Hargrove. "Age, Testosterone, and Behavior among Female Prison Inmates." Psychosomatic Medicine 59 (1997): 477-80.
Freeman, E.R., D.A. Bloom, and E.J. McGuire. "A Brief History of Testosterone." Journal of Urology 165 (2001): 371-73.
Gambineri, A., and R. Pasquali. "Testosterone Therapy in Men: Clinical and Pharmacological Perspectives." Journal of Endocrinological Investigation 23 (2000): 196-214.
Giorgi, A., R.P. Weatherby, and P.W. Murphy. "Muscular Strength, Body Composition and Health Responses to the Use of Testosterone Enanthate: A Double Blind Study." Journal of Science and Medicine in Sport 2 (1999): 341-55.
Hayes, F.J. "Testosterone—Fountain of Youth or Drug of Abuse?" Journal of Clinical Endocrinology and Metabolism 85 (2000): 3020-23.
Killinger, D.W. "Testosterone." Canadian Medical Association Journal 103 (1970): 733-35.
Mazur, A., and A. Booth. "Testosterone and Dominance in Men." Behavioral and Brain Sciences 21 (1998): 353-63.
Pope, H.G., E.M. Kouri, and J.I. Hudson. "Effects of Supraphysiologic Doses of Testosterone on Mood and Aggression in Normal Men: A Randomized Controlled Trial." Archives of General Psychiatry 57 (2000): 133-40.
Rolf, C., and E. Nieschlag. "Potential Adverse Effects of Long-term Testosterone Therapy." Bailliere's Clinical Endocrinology and Metabolism 12 (1998): 521-34.
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