Like other organs in the body, bones are constantly changing. Throughout childhood and as young adults, bones grow in strength and in size. Around the age of 30, bones reach their peak strength and then naturally become weaker with age. Osteoporosis is a condition where bones become weak to the point of breaking.

Age is an important risk factor. Both men and women lose bone strength as they grow older. Women have higher risk for osteoporosis as they have smaller, thinner frames. Women are also affected by menopause. After menopause, women produce less of the hormone estrogen, which helps protect women against bone loss.

Symptoms of osteoporosis do not occur until a lot of bone strength is lost. The most visible symptoms may include loss of height along with curvature of the upper back. Osteoporosis also can result in a crippling and painful fracture, occurring most often in the hip, back, or wrist.

There are rarely signs until a lot of bone has been lost. A medical test using a densitometer to measure the amount of bone lost is the best way to detect osteoporosis. It uses small amounts of x-ray to measure the amount of bone mineral and produces images of the spine, hip or even the whole body. The x-ray is composed of two energy levels which are absorbed differently by bones. A computer is able to determine from these differences how much bone mineral is present. The spine and hip are measured because that is where osteoporotic fractures occur most.

The test is painless and typically takes one to ten minutes. You just need to like still and breathe normally. The entire length of the visit however can take twenty to thirty minutes.

Even though x-rays are used, the amount absorbed by the patient is only about 10 percent of that received from a chest x-ray. Even though the x-ray dose from the bone densitometry test is very low, please inform the operator if you are pregnant or might be pregnant before your test!

The test compares your bone mineral density (BMD) to that of a “young adult” at peak bone strength. It also compares your results to people of your same age, called “age-matched.” This information, along with other factors, helps doctors gauge your risk of osteoporotic fracture. The difference between your result and that of a “young adult” is given a T-score. A panel of experts at the World Health Organization (WHO) has developed categories that define the amount of bone loss:

• Normal: a T-score that is above –1
• Osteopenic: a T-score between –1 and –2.5 (Low bone density)
• Osteoporosis: a T-score below –2.5

   Your T-score is one factor that your doctor will consider in making a diagnosis. The bone densitometry test is also useful in following bone changes.

The bone densitometer can monitor the effects of age, diet, or treatments on our bone status and provides information about your own risk of bone fracture in the same way a cholesterol test indicates risk of a heart attack. A diagnosis of osteoporosis cannot predict bone fracture, just as high cholesterol cannot predict a heart attack. It means that the risk of having a fracture is higher than that for normal bones.

Your test results combined with other factors give your overall risk of fracture. Knowing your risk of fracture is important. There are a number of ways to prevent osteoporosis and to reduce your risk factor. You doctor may suggest a number of steps including exercise, changes in diet, hormone therapy, or other medicines known to build bone strength.