Doctors advise bone density scans for all women over 65 and those younger with osteoporosis risk factors like menopause. Monitoring bone mineral density can help in follow-up treatment and prevent osteoporosis and bone fractures.

If you’re living with osteoporosis, you may have had a bone density scan taken to help your doctor diagnose the condition. However, your doctor may recommend follow-up scans to test the density of your bones over time.

While the scans aren’t a treatment for osteoporosis, some doctors use them to monitor how medications and other osteoporosis treatments are working.

A bone density scan is a painless, noninvasive test that uses X-rays to detect the density of bones in key areas. The scan is technically known as dual-energy X-ray absorptiometry, or DXA. Areas for scanning may include your spine, hips, wrists, fingers, kneecaps, and heels. However, sometimes doctors only scan certain areas, such as your hips.

A bone density scan may involve a CT scan, which provides more detailed and 3D images.

There are different types of bone density scanners:

  • Central devices can measure the density of bones in your hips, spine, and total body.
  • Peripheral devices are typically portable and measure bone density in your fingers, wrists, kneecaps, heels, or shinbones. Pharmacies and health stores sometimes offer peripheral scanning devices.

Hospitals typically have the larger, central scanning devices. Bone density scans with central devices may cost more than their peripheral counterparts. Either test can take anywhere from 10 to 30 minutes.

Peripheral devices generally don’t give as much information as central DXA and is less accurate. If you’ve gotten test results from using a peripheral device that indicate you have a higher risk of broken bones or osteoporosis, it is important to confirm the results with a central DXA test.

The scan measures how many grams of calcium and other key bone minerals are in portions of your bone. Bone density scans aren’t the same thing as bone scans, which doctors use to detect bone fractures, infections, and cancers.

According to the U.S. Preventive Services Task Force, all woman above the age of 65 should have a bone density test. Those younger than 65 who have risk factors for osteoporosis should also have a bone density test. Alongside age, other risk factors include a family history of osteoporosis and going through menopause, which lowers estrogen levels.

A doctor will review your bone density test results with you. Usually, there are two major numbers for bone density: a T-score and a Z-score.

A T-score is a measurement of your personal bone density compared with a typical number for a healthy young adult. The T-score is a standard deviation, meaning how many units a person’s bone density is above or below average. While your T-score results may vary, the following are standard values for T-scores:

  • –1 and higher: Bone density is normal for age and sex.
  • Between –1 and –2.5: Bone density calculations indicate osteopenia, meaning bone density is less than normal.
  • –2.5 and less: Bone density indicates you might have osteoporosis.

A Z-score is a measurement of the number of standard deviations compared with a person of your age, sex, weight, and ethnic or racial background. Z-scores less than 2 can indicate a person is experiencing bone loss that is not in line with aging.

Because bone density scans involve X-rays, you have some radiation exposure. However, the amount of radiation is considered small. If you’ve had many X-rays or other exposures to radiation over your life, you may wish to talk with your doctor about potential concerns for repeated bone density scans.

Another risk is that bone density scans may not correctly predict fracture risk. No test is always 100% accurate.

If a doctor tells you that you have a high fracture risk, you may experience stress or anxiety as a result. This is why it’s important to know what you and your doctor will do with the information a bone density scan provides.

Also, a bone density scan doesn’t necessarily determine why you have osteoporosis. Aging can be one of many causes. A doctor should work with you to determine if you have other contributing factors that you could change to help improve bone density.

While doctors use bone density scans to diagnose osteoporosis and predict a person’s risk for experiencing bone fractures, they also have value for those who already have an osteoporosis diagnosis.

A doctor may recommend bone density scanning as a means to gauge if osteoporosis treatments are working. Your doctor can compare your results to any initial bone density scans to determine if your bone density is improving or worsening.

According to the Bone Health & Osteoporosis Foundation, healthcare professionals will often recommend repeating a bone density scan 1 year after treatments start and every 1 to 2 years thereafter.

However, expert opinions are mixed regarding the helpfulness of regular bone density scans after diagnosis and once treatment is in place. An older study examined almost 1,800 women receiving treatment for low bone mineral density. The researchers found that doctors rarely made changes to a bone density treatment plan, even for those whose bone density decreased after treatment.

A more recent study found that the benefits of regular bone density scans may differ even within a person. A clinical trial study in the United Kingdom examined 12,483 women ages 70 to 85 with a high risk of fracture. It found that DXA screening did not make any difference in the occurrence of osteoporotic fractures or mortality 5 years later, but it did make a difference in reducing the risk of fractures in the hips.

If you’re taking osteoporosis medications or have made lifestyle changes to help strengthen your bones, your doctor may recommend repeat bone density scans.

Before undergoing repeated scans, you can ask your doctor the following questions to check whether repeated scans are the best choice for you:

  • Does my history of radiation exposure put me at risk for further side effects?
  • How do you use the information you get from the bone density scan?
  • How often do you recommend follow-up scans?
  • Are there other tests or measures I can take that you would recommend?

After discussing potential follow-up scans, you and your doctor can determine whether further bone density scans may improve your treatment measures.

Bone density scans are often recommended for women ages 65 and above as they have a higher risk for osteoporosis than those who are younger. However, people below 65 years who have gone through menopause may also develop osteoporosis as the decreased level of estrogen increases its risk.

It’s important to speak with your doctor to determine whether a bone scan is right for you and how often to have one. While screening for bone mineral density itself isn’t a treatment for osteoporosis, it can help monitor any progression of osteoporosis if you’ve already received a diagnosis. It can also monitor whether medications and other osteoporosis treatments are effective.