After bones reach peak strength around age 30, they slowly but naturally weaken with age. Through aging alone or combined with other factors, osteoporosis can make bones so fragile they break without warning. For many, a minor fall or misstep causes the first sign of this silent disease—a painful, crippling fracture in the hip, back or wrist.
A bone density test can help to calculate your risk of broken bones before you injure yourself.
Risk factors for osteoporosis
Both men and women lose bone strength, but women are at greater risk because their bones tend to be smaller. After menopause women produce less estrogen, a hormone that helps protect against bone loss. Other risk factors include:
- Caucasian and Asian race
- Personal and family history of bone fractures
- Advanced age
- Low body weight
- Discontinuing estrogen therapy
- Radiation therapy for cancer
Why should I have a bone mineral density test?
Osteoporosis symptoms may not occur until significant bone strength is lost. Fortunately, osteoporosis can be prevented or reversed if low bone mass is detected early. A bone mineral density test (BMD) is the first—and perhaps most important—step to find out whether your bones are as dense and strong as they should be for your age and sex.
When should I be tested and how often?
Gundersen Health System providers encourage bone mineral density tests for:
- Postmenopausal women 65 years and older, regardless of additional risk factors
- Postmenopausal women younger than 65 with one or more additional risk factors for osteoporosis, e.g., family history, previous radiation therapy, malnutrition, etc.
- Postmenopausal women who had a fracture of any type as an adult after age 45
Our providers also recommend BMD tests for premenopausal and perimenopausal women with osteoporosis risk factors
Periodic BMD tests can measure changes in bone strength and show the effects of age, diet or medical treatments. Your doctor may suggest follow-up tests to determine whether osteoporosis treatments have been effective.
How does the densitometer work?
A computerized bone densitometer aims low intensity X-rays at the spine and hip, two areas where osteoporotic fractures are more likely to occur. During the scan, bones absorb X-rays at two energy levels. (The technical term for this is “dual-energy X-ray absorptiometry,” which is why this is sometimes called a DEXA bone scan.) By comparing differences in X-ray absorption, the densitometer shows how much bone mineral is present.
What happens during the test?
A bone mineral density test is safe, quick, easy and painless. The technologist will enter your name, age, height, weight and ethnic group into the densitometer’s computer. It will compare your density measurements with others of your age and sex.
While fully dressed, you will lie still on your back on a comfortable, padded table for about 10 minutes. During this time, low-intensity X-rays pass through your hip bone and spine to create digital images.
The dose to your body during the test is comparable to naturally occurring radiation you are exposed to in a week of everyday activities. If you are or might be pregnant, you should inform your technologist before the test begins.
How will the information be used?
The technologist performing the test will analyze the scan and send results to a radiologist. This physician reviews and interprets the scan and reports findings to your provider. When your results are compared with that of a young adult at peak bone strength, the difference is called a “T-score.” The bigger the negative number, the lower your bone mass. A normal T-score is above -1. A T-score between -1 and -2.5 indicates low bone density, a condition called osteopenia. A T-score below -2.5 means you have osteoporosis.
What if my bone density is lower than it should be?
A diagnosis of osteoporosis cannot predict a bone fracture, but it means your risk of having a fracture is higher than for those with normal bone density. Knowing your risk for osteoporosis can help you prevent, reduce or reverse its effects. Your provider may recommend:
- More exercise, especially weight-bearing activities
- Changes in diet such as an increase in calcium and vitamin D
- Hormone therapy
- Prescription medications known to build bone strength
Will my insurance cover this test?
If your doctor prescribes a BMD test based on your age, family history and other risk factors, it will be covered by insurance in most cases. (Please verify your coverage with a representative from your health plan.) Medicare will cover a BMD test (a DEXA bone scan in Medicare literature) once every 24 months. If you request a bone density test without a physician’s order or more often than Medicare allows, you must pay the entire cost of the test and its interpretation by a radiologist.
How do I prepare for this test?
Seven days before the test, you should not have barium studies, nuclear medicine studies or CT scans with contrast.
On the day of the test, do not take any calcium or multi-vitamins in pill form prior to the test.