Testosterone is a key hormone in males that controls not only sexual development and performance but features as varied as hair growth, muscle development and even cardiovascular health. Low testosterone levels are associated with a number of health problems in men, which is why replacement therapies for men are becoming more accepted.
Testosterone is a natural anabolic steroid secreted by the testes and, to a smaller degree, the adrenal gland. It is the most important male sex hormone, and men normally produce 40 to 60 times more of it than women.
There are no established normal levels of testosterone in men because they vary widely according to age and individuals. Doctors in the U.S. generally consider anything below 300 nanograms per deciliter low, but those levels could be normal in an older man. Testosterone levels peak in the late 20s, dropping an average of 1.5 percent a year after age 30. A man in his 80s usually has 20 to 50 percent as much of the hormone as a man in his late 20s.
Causes of Low Testosterone
Low testosterone levels can be caused by congenital problems with the formation of the testes, though more commonly they are a result of aging, chronic illness, drugs, starvation, stress, head trauma, infections, cancers, surgeries, alcoholism or trauma to the testicles.
Symptoms of low testosterone in men are rare or often so subtle they are easy to miss, but they can include loss of sex drive, erectile dysfunction and bone loss or bone fractures. Doctors also say suffering from two of the following symptoms simultaneously may indicate low testosterone: sleep disturbance, depression, lethargy and diminished physical performance.
The most common testosterone replacement treatments consist of injections and patches, but doctors don't always agree about when they are necessary. In fact, the American Association of Clinical Endocrinologists has revised its recommendations to include hormone replacement therapy even for older men whose testosterone levels may have in the past been considered normal. Other doctors, however, reserve the treatments for younger and middle-aged men.
For injection therapy of testosterone enanthate or cypionate, doctors recommend 200 milligrams I.M. every 10 to 16 days. Serum testosterone levels one week after injection should be in the mid-normal range. For weekly injections, the therapy dosage should be reduced to 100 milligrams I.M. per injection, though dosages as high as 600 milligrams weekly have been used by some athletes to build strength and muscle mass. But these can have serious side effects. For scrotal testosterone patches, doctors recommend one on scrotal skin each morning, which should help get testosterone levels in the mid-normal range four hours later. Two patches nightly on non-scrotal areas should produce mid-normal levels eight to 12 hours after the application.