As men age, their blood levels of testosterone gradually fall. About 20 percent of men over age 60 and 50 percent of men age 80 years or older have blood levels of testosterone that are below the levels seen in healthy younger men. When the levels get low enough, men will show symptoms such as erectile dysfunction (failure to be able to get an erection), loss of sex drive, loss of muscle mass and an increase in body fat, loss of bone density and muscle weakness.
A large number of studies have been done looking at the effects of testosterone replacement in older men. AndroGel is a gel form of testosterone that is applied to the skin. Testosterone is also available in the form of a patch and as an injection. Almost all of the studies of testosterone replacement in older men have shown an increase in bone density and muscle mass, and a decrease in body fat. The results seen in muscle strength, blood levels of cholesterol, risk of heart attack and sexual function have been mixed.
There is a risk of prostate cancer and prostate enlargement with the use of testosterone replacement in older men. In at least one study, men getting testosterone replacement saw an increase in the size of their prostate. There is a possibility of an increase in a blood marker for prostate cancer called a PSA (prostate-specific antigen). The long-term effects of testosterone replacement in men with only mild lowered blood levels are not clear. None of the studies have seen an increase in the number of men with prostate cancer, however.
At the moment, most experts do not recommend the use of testosterone replacement with drugs like AndroGel unless the man has very low levels or is symptomatic. All drugs have risks. There is a risk of prostatic enlargement and at least theoretically of prostate cancer with replacement. It is important for elderly men who are taking testosterone replacement to be followed by their physician. An annual examination of the prostate with a blood test for the amount of PSA seem like good ideas.
J Am Geriatr Soc. 51(1):101-15; discussion 115, 2003 Jan.
