The Lowdown on Low Testosterone
In women, menopause is characterized by a cessation of fertility and a sharp drop in certain hormone levels at midlife. In that sense, men don't go through their own version of menopause. Instead, men generally experience a slow but steady decline in testosterone over the decades, mostly after age 50. If a man's testosterone level drops substantially (and especially if this causes adverse effects), it's often called andropause or late-onset hypogonadism—though there's much controversy about how to define this and thus how common it is.
As with menopause, pharmaceutical companies and "anti-aging" clinics are eager to medicalize andropause and market remedies for it. Direct-to-consumer ads make it sound as if many, perhaps most, older men should be taking supplemental testosterone in order to regain youthful vigor and reverse any andropause-related symptoms. How much should men worry about "low T," as the too-clever ad campaign for a prescription testosterone gel calls it?
Diagnosing Testosterone Deficiency: Seldom Clear-cut
Testosterone is the male equivalent of estrogen—a hormone that controls many aspects of sexuality as well as secondary sexual characteristics, such as facial hair, musculature, and voice quality. No one knows exactly what role declining levels of testosterone (and other hormones) play in the aging process.
Here are some points to keep in mind:
- Though researchers have come up with various sets of age-related ranges of "normal" testosterone, blood levels vary greatly from man to man, and even during the course of the day in the same man. Expert groups have different cutoff points, and no one knows what the optimal levels are.
- Estimates of how many older men have low levels for their age vary widely—from 5 to 35 percent—depending on how these are defined and which forms of testosterone (total, free, or bioavailable) in the blood are used.
- Low testosterone, however it's defined, is not a problem unless it is accompanied by undesirable symptoms ot testosterone deficiency. That's why some guidelines require the presence of such symptoms for a diagnosis of age-related hypogonadism (andropause) to be made. For example, in 2010 a major study of more than 3,000 European men (age 40 to 79), in the New England Journal of Medicine (NEJM), found that just 3 percent of men in their sixties and 5 percent in their seventies had hypogonadism, defined as low testosterone plus three sexual symptoms: poor morning erections, low sexual desire, and erectile dysfunction.
- In some men, low testosterone leads to decreased sexual drive, erectile dysfunction, loss of muscle and bone, fatigue, and other problems. Thus, supplemental testosterone is sometimes prescribed for older men with these problems, though the evidence regarding its effectiveness is mixed. These problems can have a host of other causes, of course. In fact, as was seen in the NEJM study, most men who have sexual symptoms have "normal" levels of testosterone. Moreover, most men with low testosterone levels suffer few, if any, related problems.
- Low testosterone is also often associated with conditions such as diabetes, bone loss, obesity, and high blood pressure. But it's not certain whether low testosterone is a cause or an effect of these conditions, or whether supplemental testosterone can ameliorate them. In men with osteoporosis who have markedly low testosterone levels, hormone therapy may be beneficial, but more research is needed.
- Testosterone therapy has been linked to an increased risk of prostate cancer and heart disease, along with liver damage, sleep apnea, breast growth and prostate enlargement. As with the proposed benefits, however, the evidence concerning most of these risks is inadequate or inconsistent. There have not been any large long-term clinical trials on testosterone therapy, along the lines of the famous Women’s Health Initiative study on menopausal hormone therapy. That study upended many hopes and beliefs when it found that the hormones had few benefits and actually posed serious risks.
Who needs testosterone "replacement?"
Some genetic disorders and other conditions (such as HIV infection and liver disease), as well as certain medications, may result in a dramatic drop in testosterone in young as well as older men. Such men may benefit from prescription testosterone therapy, but only on expert medical advice.
This is a serious decision, since the long-term risks are unknown. Words to wise men: Though testosterone is essential for making males masculine, lower levels as you grow older do not mean you are less of a man. Older men in good health can remain fit and stay sexually active, and many can father children. Hormone levels are only one part of the equation. Don't assume you need testosterone therapy if you feel your libido is dropping off. But if you're concerned about that or have other symptoms that may be related to a reduced testosterone level, talk to your doctor.
Source: Originally published in The University of California, Berkeley Wellness Letter (May 2011)