Between two and four million men in the US alone suffer from below-normal testosterone levels, a condition known as hypogonadism.

It’s a problem that gets progressively more common as men age, though it can also strike men at any age for a variety of reasons. Unfortunately, very few men with below-normal testosterone are getting the help they need. It’s estimated that only 5% of the millions of men with hypogonadism are currently being treated, despite a booming business in testosterone replacement therapies of many kinds. (Sales of prescription testosterone products have soared more than 500% since 1993.)

This surge in the use of testosterone products may not be an entirely good thing. Testosterone replacement therapy is only appropriate and safe for men who have below-normal levels and who don’t have any medical conditions that could be made worse by testosterone, such as an enlarged prostate or evidence of prostate cancer.

As we’ll see, use of testosterone by men with normal levels is very risky. The symptoms of hypogonadism are often overlooked, because, in part, they are mistaken for ordinary signs of aging.

The enormous industry that has sprung up to capitalize on this problem has contributed to a dangerous rise in the unregulated sale and use of testosterone supplements. Far too many men are obtaining quick-and-dirty prescriptions for testosterone, and abusing the hormone because it makes them feel temporarily younger and stronger.