What a bone density test measures and why doctors order it

A bone density test, also called a DEXA scan or DXA scan, measures how much mineral is packed into your bones. It takes a picture using very low-dose X-rays — less radiation than a standard chest X-ray — and compares your bone density to that of a healthy young adult. The result tells you and your doctor whether your bones are strong, weakening, or already thinning.

Doctors order this test to catch bone loss before a fracture happens. Weak bones (a condition called osteoporosis) often have no symptoms until you break something. A fall that would bruise a younger person can break a hip, spine, or wrist in someone with low bone density. The test helps your doctor decide whether you need treatment to slow bone loss or prevent breaks.

The test is painless, takes about 10 to 30 minutes, and you stay fully clothed. You lie on a table while a scanner arm passes over your hip, spine, and sometimes your forearm. You do not need to undress or receive an injection.

Key Takeaways

  • A bone density test uses low-dose X-rays to measure how strong your bones are and predict your risk of fracture.
  • Medicare covers the test once every two years for women 65 and older, and for men 70 and older, with no out-of-pocket cost if your doctor orders it.
  • The test takes 10 to 30 minutes, is painless, and requires no special preparation beyond removing metal objects and jewelry.
  • Your results come as a T-score, which compares your bone density to a healthy young adult; a score of −1 or higher is normal, −1 to −2.5 shows bone loss, and −2.5 or lower indicates osteoporosis.
  • If your bones are weak, your doctor can discuss treatment options, calcium and vitamin D intake, exercise, and fall prevention.

Who should have a bone density test and when

The U.S. Preventive Services Task Force recommends bone density screening for all women 65 and older and all men 70 and older. If you are younger but have risk factors — such as a family history of osteoporosis, a previous fracture from a minor fall, use of certain medications like steroids, or conditions that affect bone health — your doctor may order a test sooner.

Women who have gone through menopause lose bone density faster because estrogen, which helps protect bone, drops sharply. Men lose bone more slowly but still lose it as they age. Some people need testing more often than others. Your doctor will tell you whether you need another test in one year, two years, or longer, based on your first results and your risk factors.

If you have already been diagnosed with osteoporosis or are taking medication to treat bone loss, you may have repeat tests to see whether the treatment is working.

What to expect during the test and how to prepare

Before your appointment, remove all metal objects — belt buckles, zippers, jewelry, hearing aids, and dentures if they contain metal. Wear comfortable, loose clothing without metal fasteners. You do not need to fast or stop taking medications. Tell your doctor or technician if you have had a barium X-ray or injected contrast dye in the past two weeks, because these can interfere with results.

During the test, you will lie on your back on a padded table. A scanner arm moves slowly over your lower spine and hip, and sometimes your forearm. You need to stay still but do not need to hold your breath. The technician may ask you to move your leg into a specific position. The whole process takes 10 to 30 minutes depending on which bones are being scanned.

You will not feel anything during the scan. There is no pain, no noise, and no sensation of heat or cold. You can resume your normal activities when ready afterward.

Understanding your bone density test results

Your results are reported as a T-score, a number that compares your bone density to that of a healthy 30-year-old. The score tells you how many standard deviations above or below the young adult average your bones are.

Here is what the scores mean:

  • T-score of −1 or higher: Normal bone density. No treatment needed, but continue weight-bearing exercise and adequate calcium and vitamin D.
  • T-score between −1 and −2.5: Low bone mass, sometimes called osteopenia. Your bones are weaker than normal but not yet in the osteoporosis range. Your doctor will discuss prevention strategies.
  • T-score of −2.5 or lower: Osteoporosis. Your bones are significantly weaker and your fracture risk is higher. Your doctor will likely discuss treatment options.

Your results also include a 10-year fracture risk — the percentage chance you will break a hip, spine, or forearm bone in the next decade. This helps your doctor decide whether medication is right for you. A higher risk may lead to a prescription for a bone-strengthening drug; a lower risk may mean lifestyle changes are enough.

Cost and insurance coverage

Medicare covers a bone density test once every two years for women 65 and older and men 70 and older, with no out-of-pocket cost if your doctor orders it as a screening test. If you are younger but have risk factors, Medicare may cover it, but you should check with your plan.

Most private insurance plans cover bone density screening for women 65 and older and men 70 and older. Some plans cover it for younger people with risk factors. Your cost depends on your plan's deductible and copay. Call your insurance company or check your plan documents before your appointment to confirm coverage.

If you do not have insurance, the cost of a bone density test typically ranges from $100 to $300, though this varies by location and facility. Some community health centers offer screening at lower cost. Ask your doctor's office whether they know of low-cost options in your area.

What happens after your test: next steps and treatment options

Your doctor will review your results with you and explain what they mean for your health. If your bones are normal, you will likely be advised to continue weight-bearing exercise (walking, dancing, light strength training), eat enough calcium and vitamin D, and avoid smoking and excess alcohol. You may not need another test for several years.

If you have low bone mass or osteoporosis, your doctor may recommend medication. Common options include bisphosphonates (such as alendronate or risedronate), which slow bone loss, and other drugs that work differently. Your doctor will discuss the benefits and side effects of each option and help you decide what is right for you.

Regardless of your results, your doctor will likely discuss fall prevention — removing tripping hazards at home, wearing proper footwear, checking your vision and hearing, and reviewing medications that might make you dizzy. These steps matter as much as bone strength in preventing fractures.

Frequently Asked Questions

How much radiation does a bone density test use?

A DEXA scan uses about one-tenth the radiation of a chest X-ray. The dose is so low that the test is considered very safe, even if you have it repeated every year or two. The benefit of knowing your bone strength far outweighs the small radiation risk.

Can I have a bone density test if I have metal implants or a pacemaker?

DEXA scans use X-rays, not magnets, so metal implants and pacemakers do not interfere. However, tell your technician about any metal in your body so they can note it on your report. If you have had recent spinal surgery with metal hardware, your doctor may want to scan a different bone instead.

What if my first test shows normal bones — do I need another one?

If your bones are normal and you have no risk factors, you typically do not need another test for 10 years. If you have risk factors like family history or use steroids, your doctor may recommend testing every two to five years to catch any decline early.

Can I take calcium supplements before my test?

Yes, calcium supplements do not interfere with the test. However, some calcium products contain barium, which can show up on the scan. If you took a barium X-ray or barium drink in the past two weeks, tell your technician, as it may affect your results.

What should I do if my results show osteoporosis?

Schedule a follow-up appointment with your doctor to discuss treatment options, which may include medication, increased calcium and vitamin D, exercise, and fall prevention strategies. Do not panic — osteoporosis is treatable, and many people manage it successfully with the right plan.