It's estimated that up to 25% of all men in the United States have low testosterone (low T), although less than 6% have symptoms. Doctors don't yet understand why some men do while others don't, says Abraham Morgentaler, MD, a Harvard-based urologist and author of Testosterone for Life (McGraw-Hill, 2009). He suggests that every man has a different threshold for developing symptoms.
Levels of testosterone (also known as the male hormone) decline gradually as men age, but usually don't fall enough to cause an actual "male menopause." Because testosterone levels drop slowly, often over years, men may not notice gradual changes in how they feel, or may blame symptoms they do notice on aging. However, over time some men with low T can encounter some of the changes women experience after menopause—a higher risk of bone thinning that can lead to osteoporosis and fractures, increased irritability, problems concentrating, depression and even hot flashes.
Besides low libido, low T can lead to erectile dysfunction (ED), low energy, and low bone density. It also can result in muscle being replaced by fat.
Low T also has been linked to diabetes. It's estimated that approximately 50% of men with diabetes have low T, and that the risk of low T among men with diabetes is double that of men who don't have the disorder. Still at issue is whether testosterone replacement can help control diabetes. So far, says Dr. Morgentaler, studies have produced conflicting results.
To treat low T, testosterone injections can help. In Dr. Morgentaler's study of 211 men between the ages of 30 and 79 who had low libido, almost two-thirds reported improvement after beginning testosterone therapy, regardless of their age. Explaining why treatment didn't work for all the men in the study, Dr. Morgentaler notes that human sexuality involves more than just body chemistry. Libido can wane due to stress and other factors.
When low T is the problem, testosterone replacement also may work to remedy ED. However, there is much controversy over testosterone replacement in older men. Some studies show it can increase the risk of heart attacks and strokes and prostate cancer.
Today, most testosterone replacement is delivered through patches placed on the skin or with gels that men rub into their upper arms or shoulders. Gels, it's been found, provide for better absorption of the medication than patches. Some men also get periodic testosterone injections at their doctors' offices or inject themselves. Whatever the delivery method, dosage may have to be adjusted until a man begins to feel better.
Not every change a man experiences as he ages is due to low T. But if a guy is losing his edge, and his interest in sex isn't what it used to be, it's worth finding out if low T is the problem. If it is, boosting hormone levels may tune him up and turn him on.