'Male Menopause' Not as Simple as 'Low T'

September 12, 2013

News Review From Harvard Medical School -- 'Male Menopause' Not as Simple as 'Low T'

"Low T," or testosterone, may not cause all of the symptoms of so-called male menopause, a new study suggests. In fact, low levels of the female hormone estrogen may play a role as well, the study finds. And there was no clear cutoff for "low" testosterone. The study included 400 healthy young and middle-aged men. They were given a drug to suppress natural production of both testosterone and estrogen. Then they were given either testosterone gel (in different doses) or a placebo (fake) gel to apply for 16 weeks. In men, some testosterone is converted to an estrogen called estradiol. Half of the men also were given a medicine that blocked this from happening. After 16 weeks, the loss of either hormone was linked with reduced sexual function. Men with lower levels of testosterone had more loss of muscle mass and strength. Low estradiol was linked with increases in body fat. The drop in testosterone that caused symptoms varied a great deal among men. The New England Journal of Medicine published the study. HealthDay News wrote about it September 11.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

When you hear the word "testosterone," what's the first thing that comes to mind? 

For me, I think of muscle-bound men, macho behavior or male sexual function. High levels are supposed to predict aggressive or even violent behavior. This has been largely debunked, however.

But what about low levels? The notion that low testosterone is a common and serious problem is much more popular now than in the past. At least part of this is because of drug company marketing efforts.

There's even a new disease with its own nickname, largely invented by the drug companies! "Low T" (for low testosterone) is supposedly a common cause of symptoms such as low energy and sexual dysfunction.

But the link between low testosterone and disease is not that simple. Testosterone levels vary over the course of the day. For example, they are highest in the morning. They're also not particularly accurate at predicting the presence of disease or symptoms. Levels fall with age. We aren't even sure what testosterone levels should be considered "ideal" or whether the normal range should change with age. 

In fact, men with low testosterone levels are often healthy and feel fine. The fact that your testosterone levels are somewhat low does not mean you have a disease.

Conditions other than low testosterone also may cause similar symptoms. For example, depression is a common cause of fatigue and reduced sex drive.

A study just published in the New England Journal of Medicine explores the role of testosterone in male health. It suggests that when it comes to muscle strength, sexual symptoms and other effects of testosterone in men, there's another important factor to consider:  estrogen.

That's right. Hormones usually linked with female health and disease may actually play a role in symptoms that have been ascribed to low testosterone.

The major estrogen in men, estradiol, comes from testosterone. When testosterone drops, so does estradiol. That fact led researchers to ask:  When men have low testosterone levels, what causes their symptoms? Is it low testosterone levels, low estrogen levels or both?   

To answer this, researchers enrolled nearly 200 healthy young and middle-aged men who had normal testosterone levels. First, the men received a medicine that lowered both testosterone and estradiol. Then they were treated with a placebo or various doses of testosterone. A second group also received a medicine that blocked the production of estradiol from testosterone. 

These treatments allowed researchers to study three groups of men. The different groups had:

• Low levels of both testosterone and estradiol
• Normal testosterone but low estradiol
• Normal hormone levels

After four months, researchers found that:

• Levels of testosterone needed to promote strength, muscle mass and sexual function varied a lot between men
• Low testosterone levels were linked with decreased muscle mass and strength
• Low estrogen levels were linked with increased body fat
• The combination of low testosterone and low estradiol accounted for reduced sexual function

These findings are important because they help explain why testosterone levels alone are not a reliable way to assess symptoms often attributed to low testosterone. These symptoms include fatigue, weakness and sexual dysfunction. More importantly, this study suggests that doctors evaluating these symptoms may need to look at estrogen levels as well as testosterone.

This study shows that symptoms may not be related to the measured testosterone result. So it calls into question the common practice of automatically treating low testosterone with medicines containing testosterone.  

What Changes Can I Make Now?

Learn more about low testosterone and how it's treated. The most common cause is hypogonadism. Symptoms in men include:

• Infertility
• Erectile dysfunction and/or reduced sex drive
• Reduced muscle mass
• Reduced growth of body hair and beard
• Loss of bone (osteoporosis)
• Fatigue
• Hot flashes (similar to those of perimenopausal women)

The diagnosis of hypogonadism is based on symptoms, a physical exam and blood tests.  Other tests may include a CT or MRI scan of the pituitary gland. This is a small organ at the base of the brain. Diseases of this gland can also cause low testosterone.

Treatment will depend on the results of tests. It may or may not include testosterone.

What Can I Expect Looking to the Future?

In the future, I hope we'll have better ways to accurately determine:

• Whether low testosterone is causing a person's symptoms
• If treatment, such as testosterone replacement, should be started
• Which people are most likely to improve with treatment

Considering the results of this latest research, evaluation in the future may also include measures of estrogen levels. It could turn out that a particular balance or ratio of testosterone and estrogen is better than relying on either hormone alone.