Male hormone replacement therapy is the restoration of natural body chemicals, such as testosterone, because of the loss or absence of adequate amounts of male hormones, or androgens. Some people are born with too few androgens, and as men age, they lose the androgens that keep them young and healthy. The lack of androgens means that secondary sex characteristics — such as a lowering of the voice, a maintenance of muscle mass and fat distribution and an impelling of sexual drives — fail to appear. Hormone replacements can be natural, from humans or other similar mammals, or artificially or synthetically produced by pharmaceutical companies. Some androgens, such as testosterone, can be absorbed through the skin in the form of an ointment, and some need to be injected.
One month after conception, the adrenal gland, located just above the kidneys, begins to produce androgens that stimulate the growth of the testes in the male fetus. Two months after conception, the testes begins to produce testosterone. Testosterone levels in men are greatest just before they reach their 20s. By 80 years of age, they are at half those levels.
Normal activated testosterone levels in men are only half the actual levels of testosterone in their blood, because half or more of the hormone is bound by sex hormone-binding globulin, a naturally occurring chemical in the blood that increases with age, causing testosterone levels to decline. This slow decrease in the production of testosterone in men as they age is called andropause. It starts in middle age and is a major reason for male hormone replacement therapy in a male population seeking perennial health and youth.
Hormone levels in the human body are regulated by a feedback loop with the pituitary gland, a tiny gland at the base of the brain that controls the body’s metabolism. When the levels of hormones are artificially increased, the pituitary reduces its production of stimulating hormones, and less testosterone is produced. This feedback cycle causes the expected results from testosterone replacement therapy, such as muscle mass buildup and a cure for erectile dysfunction, to be rarely seen, although there are the youthful side effects of an increase in sexual appetite and decrease in body fat.
Sometimes there is a problem with testosterone production when the reproductive, sperm tissue of the testes do not get a signal from the pituitary to start hormone production. Called hypogonadism, this condition can occur in grown men as well as in infants, and it causes about 1 percent of all babies to be born sexually abnormal. Out of these infants, one out of 10 — or 0.1 percent of all babies — is assigned a gender by the attending physician, dependent on the baby’s genetic and physical characteristics. That would amount to approximately 300,000 intersex people in a population of 300 million. These intersex individuals, along with physically normal females who identify as male transsexuals, can benefit from male hormone replacement therapy to attain their desired sexual identity, that of a male.
Male hormone replacement therapy, as in the case of androgen replacement in older individuals, is not the end-all panacea that many men anticipate when they hope for eternal youth. Some androgens do help to bulk up muscle mass and reduce body fat and might fight osteoporosis in men, resulting in the more youthful functioning of their aging tissues and organs. Research into testosterone replacement has uncovered several counter-indications, or dangers, to individuals in long-term use, including liver damage through toxicity, feminization due to the liver converting some testosterone into estrogen and the possibility that repeated use of the hormone might stimulate prostate cancer or other hidden cancers.