CLEVELAND, Ohio -- If you pay attention to television commercials, you may be seeing ads touting the life-changing properties of Axiron, a testosterone-replacement therapy that is applied under the arm like deodorant, and Androgel, a clear gel that comes in a pump.

Treatment for low testosterone in men -- the condition is also called hypogonadism -- has been around for decades. But in recent years, the therapy has shifted from injections in the doctor's office to topical gels that can be used at home.

Androgel, the first topical gel, was approved by the Food and Drug Administration in 2001. Testim followed in 2002, then Axiron came along in 2010. The first testosterone skin patch was approved in 1995. A new lower-dose version of the Androderm patch, which is changed daily, was approved in October 2011.

More younger men -- men in their 30s and 40s -- who are bothered by fatigue, loss of libido and less-than-virile sexual function are turning to medication to treat "Low T." Some of them view the condition as some sort of deficiency. Take more of what's missing and everything will be OK.

And that concerns Dr. Bryan Hecht.

Dr. Bryan Hecht

A reproductive endocrinologist and fertility specialist at University Hospitals Fertility Center West on Crocker Road, across from Crocker Park, Hecht works with couples who have fertility challenges.

The majority of the men he sees do not have low or nonexistent levels of sperm.

But for those who do, Hecht says, testosterone-replacement therapy is to blame more and more.

Testosterone improves libido and sexual function. But in large doses, it also can suppress the body's ability to produce sperm. That's just one of the many side effects that in recent years have prompted the Food and Drug Administration to spell out all of the possible side effects.

"Historically, the majority of men [treated for low testosterone] tended to be somewhat older," Hecht said. "That's why I think the impact on fertility hasn't gotten a whole lot of emphasis."

In fact, Hecht said, he and his colleagues have noticed that some review articles that appear in scientific journals don't mention infertility as a possible side effect or complication.

As part of the safety information on the Axiron website, a lower sperm count is listed as a possible side effect, but a 41/2-minute video on applying the gel doesn't mention the risk until 3 minutes, 53 seconds.

What Hecht says alarms him is that there is no recognition on the part of men that they should avoid testosterone therapy, at least while they're dealing with fertility issues.

Recently Hecht met with a man in his early 30s who, tests showed, had no sperm. When Hecht found out that the man had been taking Androgen, prescribed by his primary physician, to boost his libido and lessen fatigue, he told him to discontinue taking it. Within a few months, the man's sperm count was normal and his wife became pregnant.

Testosterone injections are more potent than topical products in disrupting sperm production, Hecht said. Not all men have adverse effects, but it can take several months to regain normal sperm levels in those who do.

"While the treatment may be perfectly appropriate in certain men, it could potentially have an impact on fertility," he said. "The prescriber should at least be cognizant."

When patients are referred to Dr. Edward Cherullo, a urologist at UH Case Medical Center, it's often because the man has suggested to his primary physician that he might have "Low T."

Dr. Edward Cherullo

Unless a man has profoundly low testosterone levels, Cherullo says he's slow to supplement testosterone in his patients without looking into various potential causes.

If a blood test shows a moderately low testosterone level just under the reference range of "normal," adding testosterone to get it within that "normal" range is not necessarily the answer to address a nonspecific problem, Cherullo said.

Some of the symptoms of extremely low testosterone levels include profound weakness, loss of muscle mass and general confusion. But those symptoms usually don't happen in men in their 30s, 40s and 50s, who may instead have more-general complaints like fatigue, loss of libido and weight gain.

"I need to know why it's low," Cherullo says. "I actually see a number of guys where that's not flushed out [by their primary care physicians]."

Because diagnosing low testosterone is not an exact science, it's important to find out the cause first. It could be any number of things, from low hormone levels caused by an underactive pituitary gland to obesity, diabetes, sleep apnea or even low vitamin D levels.

Before he writes a prescription for testosterone therapy, Cherullo says, he has the fertility talk with his patients. It's something that most men haven't given a thought to, he said.

Surprisingly, Cherullo said he's not annoyed by the explosion of "Low T" direct marketing.

"It raises the issue, which makes it easier to talk about," he said.