There's been much public education about the need to protect women from osteoporosis, a condition that causes weakened bones.

But did you know that 2 million of the 10 million people with osteoporosis in the United States are men? I think it's time to highlight how this debilitating condition also affects men.

In women, osteoporosis is most commonly triggered by a drop in estrogen during menopause. Estrogen is required to maintain bone density and strength. The most important male hormone, testosterone, is also critical for bone strength and density, so you should not be surprised to learn that osteoporosis in men results mainly from low levels of testosterone. Low testosterone levels in men occur either as a natural consequence of aging or from some underlying disorder.

In recent years, however, men have faced another potential reason for testosterone deficiency: the growing use of androgen-deprivation therapy (ADT) to treat prostate cancer. As prostate cancer develops, cancer cells initially require testosterone to continue their growth. ADT is used to "starve" the cancer cells. (Unfortunately, over time surviving prostate cancer cells are able to grow even without testosterone).

Androgen-deprivation therapy once involved castration (surgical removal of the testicles). Today it's more likely to involve taking hormone combinations that quickly stop testosterone production.

ADT was first used mainly to treat men whose prostate cancer was inoperable and widespread. Now it is also given to men at earlier stages of prostate cancer, placing these men at higher risk for severe osteoporosis and fractures.