Male Hormone Replacement
Testosterone is the male sex hormone produced in the testes and the adrenal glands. Itís needed for the development and growth of male sex organs.
Itís also important for building strong muscles. Levels of testosterone production peak around 20, then gradually decline thereafter. Between 40 and 70, levels of testosterone decline by about 1.6 percent each year.
The decrease in testosterone follows the aging process. As they age, men also experience a decline in lean body mass, muscle mass and muscle strength. Levels of visceral fat increase, accompanied by higher incidence of glucose intolerance and cardiovascular disease.
Decline of testosterone production is a natural occurrence for aging men. If levels drop too low, men may experience mood changes, sexual dysfunction, bone loss, muscle atrophy and mental changes. Doctors can prescribe testosterone replacement therapy to restore some hormone balance. However, some people advocate testosterone replacement in aging men with normal testosterone levels. In these cases, therapy is an attempt to restore youthful strength and stamina. Researchers report two million prescriptions were written for testosterone replacement therapy in 2001.
Health experts are concerned about the growing demand for testosterone replacement in otherwise healthy men. Treatment is not without risk. Studies show testosterone replacement may be associated with an increased chance for sleep apnea and breast enlargement. There is also a theoretical increased risk for prostate cancer. The recent studies highlighting potential dangers of hormone replacement therapy in women may hold similar concerns for men.
Public health officials have urged small-scale studies to fully investigate the effects of hormone replacement on aging men. The Hormone Regulators of Muscle and Metabolism in Aging (HORMA) study is examining the effects of testosterone and another important hormone, growth hormone, in men over 65 (growth hormone levels also decline with age). Researchers theorize growth hormone may amplify the effects of testosterone.
Participants will be randomly assigned to one of two doses of testosterone (in the form of AndroGel) and growth hormone or a placebo. The study will last for 16 weeks, with a follow-up scheduled three months later. Prior to the start of the study, patients will receive a health assessment which includes blood tests, chest X-rays and electrocardiograms. Study subjects will return periodically for evaluations of general health, endurance and measurements of muscle and fat mass. In addition, muscle biopsies will be performed to examine changes in muscle fibers.
In another part of the study, researchers are testing resistance training and testosterone therapy to determine if the combined treatment may increase muscle building and decrease fat. Resistance training with weights helps to increase muscle mass and strength. But many older men donít have the energy or stamina to perform the exercises. The investigators hope to show that short-term use of testosterone may provide enough boost in muscle strength and stamina to enable seniors to start and continue a program of resistance training, which will help them maintain the gains in muscle strength and stamina. Researchers say thereís another potential advantage. Strong muscles help the body fight infection. So seniors who build muscle mass may be better able to fight disease.