Testosterone The good and the bad

WebMD When you think of testosterone, you probably think of the rough and rugged. Its one of the things that make men men. But even this most masculine of hormones requires a delicate balance.

Produced by the testes though womens ovaries make some, too, the hormone propels prepubescent boys toward deeper voices and hairy chests. In a grown man, it fuels a healthy libido, builds muscle mass and helps maintain his energy levels. But too much of it or too little can wreak havoc on a mans behavior and physique.

Why more isnt always better

According to a study in the April 1999 Journal of Behavioral Medicine, higherthanaverage testosterone levels offer certain benefits but also carry some serious risks. Researchers at Pennsylvania State University in University Park, Pennsylvania, reviewed the records of 4,393 men between the ages of 32 and 44 who had served in the military between 1965 and 1971. Their blood had been drawn to determine testosterone levels which ranged from 53 to 1,500 nanograms per deciliter, with an average of 679. The normal range in males is 270 to 1,070 nanograms.

Men whose testosterone levels were slightly above average were 45 percent less likely to have high blood pressure, 72 percent less likely to have experienced a heart attack and 75 percent less like to be obese than men whose levels were slightly below average. These men were also 45 percent less likely to rate their own health as fair or poor.

But the results werent all rosy. These men were also 24 percent more likely to report one or more injuries, 32 percent more likely to consume five or more drinks in a day, 35 percent more likely to have had a sexually transmitted infection, and 151 percent more likely to smoke.

The news got worse at very high testosterone levels 1000 nanograms, where men were even more likely to engage in risky behavior and less likely to reap the positive health benefits of testosterone.

The results arent really surprising, says lead author Alan Booth, Ph.D., a professor of sociology and human development, because testosterone has been associated with risky behavior in many studies. Men with high testosterone levels are more likely to be involved in criminal activity and antisocial behavior, get in trouble in school, remain single and be unemployed.

But this doesnt mean that all men with high testosterone levels are doomed to a bad fate, he said. Theres lots of high testosterone people out there with good marriages who dont commit crimes.