Harvard Men's Health Watch

On call: Proscar and osteoporosis

On call

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.

Bones respond directly to testosterone, as do many other male tissues: testosterone produces the strong, large muscles, deep voice, facial and body hair, sex drive, and tendency toward aggressiveness that characterize the male gender by acting directly on a man's organs and tissues. But the prostate and the scalp's hair follicles are a bit different. To affect these organs, testosterone must first be converted to dihydrotestosterone (DHT). In turn, DHT stimulates the prostate and stuns the scalp hair, producing unwelcome changes in many men.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »