Bone Density Test

What is a Bone Density Test?

A bone density test, known as DEXA scan stands for “dual-energy X-ray absorptiometry” is used to determine the concentration of calcium and other minerals in your bones. The most commonly tested bones are in the spine, hip, and sometimes the forearm. A bone density scan uses very low doses of radiation. It is safe for most people. However, it is not recommended for pregnant women as even a small of radiation can harm the baby.

Why is it done?

As we get older, our bones become thinner. When bones become thinner, this is a condition called osteopenia. Osteopenia can progress into osteoporosis, a disease in which your bones become very thin and brittle, prone to fractures.

This is a test necessary to determine whether you have osteoporosis. If your bones have a high concentration of minerals, they will be stronger. The stronger bones mean less chance of fracture. A bone density scan is used to:

• Diagnose osteopenia (low bone mass)
• Diagnose osteoporosis
• Predict risk of future fractures
• See if treatment for osteoporosis is working

Who need DEXA scan?

Most people, especially women older than 65 should have a bone density scan. Older women are at high risk for osteoporosis as they lose protective effects of estrogen on bones after menopause. Because of that it is important if you had any fracture, especially in older age to have DEXA scan. In addition, in case you aren’t physically active, smoke cigarettes, drink alcohol or/and don’t get enough calcium and vitamin D in your diet, you are more prone to osteoporosis.

How to prepare for the scan?

DEXA scan is easy, fast, and painless and there is no special preparation. It is important just to tell your doctor in case you have recently had a barium exam or some CT exam with contrast injection. This might interfere with your results. Also, you should stop calcium supplements for at least 24 hours in case you are taking them.

How to interpret the results?

A DEXA scan determines the bone mineral density (BMD). Firstly, your BMD is compared to healthy 25-35 age young adults. This is your T-score. If your T-score is from -1 to +1, this is a normal result. In case your T-score is -1 to -2.5, this means you have osteopenia and if it is below -2.5 then you have osteoporosis. Another comparison is with your age, sex, weight, and ethnic or racial origin. This is presented as Z-score. If your Z-score is significantly higher or lower than the average, you may need additional tests to determine the cause of this.

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