In older men, it's low testosterone that has captured attention.
Testosterone, the male hormone, plays a vital role in many body functions, and low testosterone levels can leave men tired, uninterested in sex, infertile and with thinning bones, according to the US National Library of Medicine.
It's also a fairly common problem in older men. As many as 4 in 10 men older than 45 have lower than normal levels of testosterone, according to the American Urological Association.
But, replacing lost testosterone isn't a panacea, despite what you might have seen on TV.
"There's been a lot of advertising, and every guy that comes in now asks about testosterone," said Dr Ryan Terlecki, a urologist at Wake Forest Baptist Medical Centre in Winston-Salem, N.C. "They've been led to believe that it's a fountain of youth, but it's not a cure-all."
For example, many men hope that testosterone therapy will help treat erectile dysfunction. But, Terlecki said that though testosterone is a treatment for low libido and taking replacement testosterone may increase a man's sex drive, it's not a direct treatment for erectile dysfunction.
Testosterone replacement also isn't an option for men who want to preserve their fertility. That's because when a man takes testosterone therapy, the testosterone receptors in the body tell the brain that there's enough testosterone, and, in turn, the brain signals the testes to stop producing sperm.
Not for cancer patients
Men who have active prostate cancer or male breast cancer also aren't candidates for testosterone therapy.
However, other men with symptoms of low testosterone may want to consider it. For starters, that includes men who "might notice a drop in energy and low libido", Terlecki said.
Dr Steven Canfield, chief of urology at the University of Texas Health Science Centre at Houston, said symptoms of low testosterone that men might notice also include "the development of breast tissue, a loss of body hair, small or shrinking testicles, no need for shaving, flushing, sweats and bone loss."
But, he said, there are
less specific symptoms, too. Men with low testosterone might also notice
"a decrease in self-confidence, feeling sad or depressed, problems with
sleeping, memory problems, reduction in body mass, and a decrease in work
Low testosterone a problem in cancer
A simple blood test
All it takes to tell if a man's testosterone level is low, he said, is a simple blood test.
Although low testosterone is common in older men, it's not necessarily a normal part of ageing. Other conditions that are common with ageing, such as obesity or depression, can cause lower levels of testosterone, according to research presented at the Endocrine Society meeting in Houston this year.
Canfield said that
testosterone levels can drop if testicular tissue is lost, which can happen with
age. And Terlecki said that prior testicular trauma, undescended testicles and
radiation treatment to the testicles also can cause lower testosterone levels.
Testosterone therapy ups risk of bad outcomes in older men
Several options exist for treating low testosterone. For men who want to keep their fertility, Terlecki said, the drug clomiphene can be prescribed. In men for whom that's no longer an issue, testosterone replacement therapy can boost testosterone levels.
Options for testosterone replacement, Canfield said, include injections, patches, a gel and implantable pellets. He said that a pill form of testosterone is available in other parts of the world, but not in the United States.
Injections are given once every two weeks, Terlecki said. The downside to this option is that injections provide a large dose of testosterone in the beginning but it drops fairly quickly.
Topical formulations, such as testosterone gel, are put on in the morning and absorbed within two to six hours and, if used consistently, provide a steady consistent dose of testosterone.
Patches can provide a longer-term steady dose of testosterone, but they may cause irritation, Terlecki said. And implantable pellets, according to Canfield, can provide a steady, long-acting dose of testosterone. They're injected just underneath the skin on your backside during an outpatient office procedure.Risks of testosterone therapy
Risks of testosterone therapy include an increase in the size of the prostate, water retention, worsening sleep apnoea, a lower sperm count and an increase in the platelet count, which could increase the risk for blood clots, according to Canfield.
Both men agreed that testosterone therapy won't solve all male health issues.
"The most important thing men need to know is that testosterone therapy isn't a substitute for taking care of overall health," Terlecki said. "A lot of men come in obese, with a poor diet and no exercise, and they want to blame low testosterone. While testosterone may play a role in their overall health, it needs to be viewed in context with these other factors."