Low libido? Testosterone therapy could help men, but it also has risks

By Deborah Kotz, Globe Staff

Men may have seen ads asking whether they’ve “lost that loving feeling” and wondered whether they should get their testosterone levels tested. The promises made by pharmaceutical companies pitching testosterone creams or gels directly to men sound too good to pass up: bigger muscles, more energy, stronger sex drive. And prescriptions for the therapy have jumped more than 500 percent over the past two decades.

Whether men should get tested and treated for “low-T” -- as drug company ads call it -- remains controversial because of unknown risks of long-term testosterone therapy and hints that it could cause life-threatening health problems in older men who tend to have the lowest levels.

Researchers at the New England Research Institutes are conducting an observational study involving nearly 1,000 men over age 18 who are being treated with long-term testosterone therapy to boost low hormone levels in order to determine whether it raises their risk of prostate cancer.

A 2010 study published in the New England Journal of Medicine found that men over 65 years of age with low testosterone levels who were treated with a daily testosterone gel for six months gained muscle strength and endurance compared with those who used a placebo gel but also had more heart attacks. Out of 209 study participants, 23 in the testosterone group had a heart attack, a blocked artery that required treatment, or died of heart problems during the study, compared with 5 in the placebo group.

Testosterone treatment also has side effects including shrunken testicles, hair loss, acne, breast enlargement, and sterility.

Just as women experience declining estrogen levels as they age and get close to menopause, men also experience a slowing in their production of testosterone as they hit mid-life. What’s more, a study published last month suggests that men today have lower testosterone levels than in decades past, possibly due to increasing rates of obesity and exposure to more chemicals in plastics and other substances that disrupt the production of sex hormones.

About 2 to 5 percent of men under age 40 have low testosterone, according to Dr. Brad Anawalt, chief of medicine at the University of Washington Medical Center and chair of the Endocrine Society’s Hormone Health Network. The percentage gradually rises to the point that one in four men over age 70 have low levels. But just as most women don’t need hormone replacement therapy after menopause, men usually don’t need testosterone replacement in their senior years. “It all depends on how much they’re bothered by symptoms,” said Anawalt.

He also recommends against routine testing of testosterone levels if a man is having vague symptoms such as feeling tired or out of sorts. “One of the real tip-offs of low testosterone is a decline in sex drive,” he added. “Most of us advise against routine testing unless a man has specific symptoms like decreased libido, sexual fantasies, pleasure in sex, and morning erections.”

Those symptoms can also be accompanied by depression, decreased muscle strength and endurance, and low energy. Men with osteoporosis are also more likely to have low testosterone levels, and Anawalt said he frequently tests hormone levels in those with severe bone loss.

Getting a proper reading on a test can be tricky, however, because blood tests can be notoriously unreliable. Because testosterone levels tend to decline throughout the day, getting tested between 7 and 10 a.m. is ideal. “About 15 percent of men with normal testosterone levels in the morning will have a reading that comes back low later in the day,” Anawalt said. “I get a lot of referrals from doctors who took the test at the wrong time of day or who used a type of free testosterone test that often comes back with a false low reading.”

Men also need to have more than one testosterone test to verify a low reading because respiratory infections and other illnesses can temporarily suppress testosterone levels.

“I think testosterone tests, when done correctly, can be a good measure of a man’s metabolic health,” said Dr. Martin Miner, co-director of the Men’s Health Center at Miriam Hospital in Providence. Low testosterone levels have been associated with type 2 diabetes, cholesterol abnormalities, chronic lung disease, and obesity, but that doesn’t mean low levels of the hormone cause these conditions, nor that treatment with the hormone can reverse them.

“My bias is towards treating men who have signs and symptoms of testosterone deficiency,” Miner said. After reviewing the latest scientific literature, he said he’s not too concerned about potential health risks and sees evidence of potential long-term benefits.

A 2012 study involving 1,031 male veterans with a testosterone deficiency who were followed for up to five years found that those who were given testosterone gels or creams had a 10 percent risk of dying during the course of the study compared with a 20 percent risk in those with low levels who weren’t treated. The researchers from Veterans Affairs Puget Sound Health Care System acknowledged, however, that certain confounding factors, such as better quality health care, might have accounted for the testosterone takers’ decreased mortality.