About 5 million American men don’t produce enough of the hormone, according to the National Institutes of Health. A study in Europe published a decade ago found one in five men over 50 has moderate-to-severe symptoms of testosterone deficiency. Fewer than 2 percent of cases outside the U.S. get treated, Malcolm Carruthers at London’s Centre for Men’s Health, wrote in a 2009 paper.
“Like global warming, awareness of the effects of testosterone deficiency is also increasing as the general public surf the oceans of information available on the Internet, but still the condition remains largely unrecognized and untreated,” Carruthers wrote.
Replacement therapy has been used since the 1930s to treat men with medical conditions, such as Klinefelter’s syndrome, that cause testosterone deficiencies leading to low energy, poor concentration, reduced sex drive, loss of muscle strength, and increased risk of osteoporosis.
Athletes, especially sports amateurs, have used testosterone to boost muscle growth since the 1950s, and cyclist Armstrong said last month he took the banned performance- enhancing hormone alongside erythropoietin and blood transfusions. The hormone can be administered via injections, gels, patches, pills and gum tablets known as troches.
“It’s very popular,” Handelsman at the University of Sydney said in a telephone interview. “Nobody dislikes being on testosterone. It’s mood-elevating.”
It does pose potential health risks. In men, high levels can cause symptoms such as acne, aggression, impotence, liver dysfunction, testicular atrophy and sperm reduction, breast enlargement and baldness.
A study of testosterone use in elderly males, funded by the U.S. National Institute on Aging and run by Shalender Bhasin at Boston Medical Center, was stopped in 2009 because an audit found it caused more heart attacks and hypertension.
“People who use it at very high doses can become manic and can fly off the handle and become dangerous,” Handelsman said.