DENVER -- Almost 8 million women in this country have osteoporosis and another 30 million are at risk.

You might think osteoporosis is an old-age disease, but any woman who is nearing menopause could be at risk.

A quick and simple test called a 'bone scans' that can tell doctors just how healthy you are.

Nancy Simon is now a regular fixture around the track at the Littleton YMCA, but she hasn't always been so dedicated.

At one time Simon hardly ever thought about exercise until she found she had osteoporosis.

"I was surprised at the diagnosis and a little concerned about the diagnosis so I felt I had to get proactive about the whole business of osteoporosis," said Simon, osteoporosis patient.

Like many women, Simon didn't think she was at risk even though she had passed menopause.

Lack of estrogen is the biggest factor in osteoporosis. It causes the bones to break down more than they build up.

Bones are literally eaten away as the body, that may also be starved for calcium, steals it from a ready source.

"So as soon as that bone gets the message that I have to give some of my calcium up, it will really leach that from the bone to maintain the serum calcium most of the time," said Dr. Kelly McAleese, Women's Imaging Center.

A bone density scan is a test that can detect osteoporosis in its earliest stage. It is very much like an X-ray. It is typically performed on women who have passed, or are approaching, menopause.

A family history can make a woman more susceptible to osteoporosis. But other factors -- like smoking and drinking -- can also increase the risk. And it's possible that a woman can have osteoporosis and not know until she starts feeling pain.

That's what happened to Simon. But now her sore lower back, thanks to exercise and medication designed to fight osteoporosis, doesn't bother her anymore.

Osteoporosis can be prevented but health experts say you need more than just calcium. You also need to make sure you body is absorbing the calcium and make sure you get exercise.

By the way some men are also at risk for osteoporosis. They make up about 20 percent of the patients.

Osteoporosis: Are You At Risk?

If you are a woman and nearing, or past, menopause, you could be at risk if:

Did you or your mother lose height, heave a curved back, or break a hip, wrist, or spine after age 50?

Are you a Caucasian or Asian?

Do you have a small, thin frame?

Have you ever been a smoker?

Do you have or have you ever taken oral steroids, such as prednisone?

Osteoporosis Prevention:

Get plenty of calcium, preferably in your diet, or take a calcium supplement.

A woman age 50 should get 1000 to 1200 milligrams of calcium everyday, plus 400 units of Vitamin B to help your body absorb the calcium.

Get exercise. Walking or jogging is good because both are weight-bearing exercises. They force your skeleton to support the weight of your body.

If you smoke, quit.

If you drink, cut back.

And also be sure to talk to your doctor before beginning any exercise or diet plane.