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Proscar and osteoporosis

Q. I am 76 years old, and I've had an enlarged prostate for at least 10 years. I've been taking Proscar for about a year, and it seems to be helping quite a bit. I have not noticed any side effects, but I'm worried that if the medicine reduces testosterone levels enough to shrink my prostate, it will also give me osteoporosis. Should I change medications, or take Fosamax like my wife?

A. The prostate gland is stimulated by testosterone, the major male hormone; that's a bad thing for older gents at risk for benign prostatic hyperplasia (BPH; an enlarged gland), or prostate cancer. Testosterone also increases bone calcium content, a good thing. Finasteride (Proscar) and its newer rival, dutasteride (Avodart) block the action of testosterone in the prostate, but they will not interfere with bone mineralization. It sounds like a paradox, but it's not. Here's why.