Excerpt from THE HIGHS AND LOWS OF TESTOSTERONE (NY Times)
By Randi Epstein
Getting a high testosterone reading offers bragging rights for some men of a certain age — and may explain in part the lure of testosterone supplements. But once you are within a normal range, does your level of testosterone, the male hormone touted to build energy, libido and confidence, really tell you that much?
Probably not, experts say.
Normal testosterone levels in men range from about 300 to 1,000 nanograms per deciliter of blood. Going from one number within the normal zone to another one may not pack much of a punch.
“You don’t see the big improvement once men are within the normal range,” said Dr. Shalender Bhasin, an endocrinologist and professor of medicine at Harvard Medical School. The largest differences in terms of energy and sex drive are when men go from below-normal to normal levels.
A 2015 study in JAMA found that sex drive improved among men who went from about 230, considered low, to 500, around the middle of what’s considered normal. There was no difference among men who moved within the normal range from 300 to 500.
Testosterone does influence muscle size. The more testosterone a man takes, the larger the muscle — regardless of starting level, one reason the hormone is popular with young bodybuilders. But testosterone supplements do not seem to help frail older men walk farther or get out of chairs more easily, goals that doctors typically look for in aiding older patients.
Beginning at age 30, testosterone levels drop, on average, about 1 percent a year. About 5 percent of men between the ages of 50 and 59 have low levels of testosterone along with symptoms like loss of libido and sluggishness, according to a few small studies.
The Food and Drug Administration approves testosterone gels and shots only for men with levels under 300, including those who have diseases that cause hormone levels to plummet, such as a pituitary tumor or injury to the testicles. Those men are truly lacking the hormone, so returning the levels to normal can help restore sex drive and energy.
Keith Hall, a 48-year-old petrochemical operator from Baytown, Tex., sought out a men’s health doctor at Baylor College of Medicine because he was tired and lacked libido. His initial testosterone level was below normal, around 202. The urologist he ended up seeing, Dr. Alexander Pastuszak, offered him testosterone shots that raised his levels into the normal range and made him feel better.
Edward Blake, a 53-year-old forklift driver from Houston, sought out the same doctor for the same reasons. His testosterone measured 450, within the normal range. “I was feeling kind of tired and stuff, but after the third shot, I’m lifting things with no problem,” said Mr. Blake. He said in addition to feeling stronger, his sex drive improved.
Dr. Pastuszak said he primarily prescribes testosterone to men in the F.D.A.’s low category but will sometimes let other men with symptoms try it. “If you have these guys in the midrange and you put them on it, the majority will say they want to stay on it,” he said, adding that most men will say it makes them feel better and boosts their sex drive.