The main test is a bone density scan called a DEXA scan

A DEXA scan (dual-energy X-ray absorptiometry) is the standard way doctors measure bone density and diagnose osteoporosis. It takes pictures of your bones using very low-dose X-rays — about one-tenth the radiation of a chest X-ray — and compares your bone density to that of a healthy young adult. The scan takes 10 to 30 minutes and is painless; you lie on a table while the scanner moves over your hip, spine, and sometimes your forearm.

Your doctor will order a DEXA scan if you have risk factors for bone loss, such as being over 50, having a family history of osteoporosis, taking certain medications like corticosteroids, or having gone through menopause. Men over 70 and women over 65 are often screened even without specific risk factors. The scan produces a report with two numbers: your T-score and Z-score, which tell your doctor how your bones compare to others your age and to young healthy bones.

Key Takeaways

  • A DEXA scan is a quick, painless X-ray that measures bone density and is the standard test for osteoporosis diagnosis.
  • Your T-score tells you whether your bones are normal, show early bone loss (osteopenia), or have osteoporosis.
  • Other tests like blood work, ultrasound, or CT scans may be used if DEXA results are unclear or if your doctor needs more information.
  • You do not need to fast or prepare specially for a DEXA scan, though you should remove metal objects and tell your doctor about recent barium or contrast dye procedures.
  • Repeat DEXA scans are usually done every one to two years to track whether your bone density is stable or changing.

Understanding your DEXA scan results

Your DEXA report will show a T-score, which compares your bone density to a healthy 30-year-old. A T-score of −1.0 or higher is considered normal. A score between −1.0 and −2.5 means you have osteopenia, or early bone loss. A score below −2.5 means you have osteoporosis. The lower the number, the weaker your bones are.

The report also includes a Z-score, which compares your bone density to others your same age and sex. A Z-score that is much lower than expected may signal that something other than aging is causing bone loss — such as a hormone problem, medication side effect, or digestive disorder — and your doctor may order additional tests.

Your doctor will discuss what your scores mean for your individual situation. Having osteopenia does not automatically mean you need medication; your doctor will also look at your age, sex, other health conditions, and fracture risk before deciding on treatment.

Other tests your doctor might order

If your DEXA results are unclear or if your doctor suspects a specific cause of bone loss, you may have additional tests. Blood work can check your vitamin D level, calcium level, kidney and liver function, and thyroid hormones — all of which affect bone health. A high-sensitivity C-reactive protein test may show inflammation linked to bone loss.

Ultrasound of the heel bone is sometimes used as a screening tool, especially in primary care offices, though it is less precise than DEXA. A CT scan (computed tomography) can provide a three-dimensional picture of bone structure and may be ordered if you have had a fracture or if your doctor needs to assess fracture risk more carefully. Bone turnover markers — blood or urine tests that measure how quickly your body is breaking down and rebuilding bone — can help your doctor decide whether medication is needed and how well treatment is working.

What happens during a DEXA scan appointment

When you arrive for your DEXA scan, you will be asked to change into a hospital gown or wear loose clothing without metal zippers or buttons. Tell the technician if you have had any barium studies or injections with contrast dye in the past week, as these can interfere with results. You do not need to fast or stop taking medications before the scan.

You will lie on a padded table while the scanner arm moves slowly over your body. You need to stay still but do not need to hold your breath. The technician may ask you to move your arm or leg into a specific position. The scan itself is quiet and painless. Afterward, you can return to your normal activities right away — there are no restrictions and no side effects.

Your doctor will receive the results within a few days to a week and will contact you to discuss them and any next steps, such as changes to diet, exercise, medication, or follow-up testing.

How often you should be tested

If your initial DEXA scan shows normal bone density, your doctor may recommend repeat screening every 10 years if you are a woman over 65 or a man over 70 with no risk factors. If you have osteopenia, repeat scans are typically done every one to two years to see whether bone loss is progressing. If you have osteoporosis or are taking bone-strengthening medication, your doctor will usually repeat the scan every one to two years to monitor how well treatment is working.

Your doctor may recommend more frequent testing if you have had a fracture, are starting or stopping certain medications, or have other health changes that affect bone health. Discuss with your doctor how often you should be screened based on your individual risk factors and medical history.

Preparing for your DEXA scan

DEXA scans require very little preparation. Wear comfortable, loose clothing without metal fasteners — metal interferes with the X-ray images. Remove jewelry, eyeglasses, and hearing aids before the scan. If you take calcium supplements, ask your doctor whether to take them the day of your scan; some doctors prefer you to skip them that morning to avoid interference, though this is not standard practice everywhere.

Bring your insurance card and photo ID. If you have had previous DEXA scans at another facility, ask if those images can be sent to your current provider so your doctor can compare results over time. Let your technician know if you are pregnant, have had recent surgery on the area being scanned, or cannot lie still for 10 to 30 minutes.

What to do if you cannot have a DEXA scan

Some people cannot have a standard DEXA scan — for example, if they are too large for the scanning table, cannot lie still, or are pregnant. In these cases, your doctor may order a peripheral DEXA scan, which measures bone density in your forearm or heel using a smaller, portable scanner. Results are less precise than a full-body scan but can still help your doctor assess fracture risk.

Quantitative ultrasound (QUS) is another alternative that uses sound waves instead of X-rays to measure bone density in the heel. It is faster and requires no radiation, but it is less accurate than DEXA and is mainly used for initial screening rather than diagnosis. If you have concerns about radiation or cannot access DEXA for any reason, talk with your doctor about which alternative test might work for you.

Frequently Asked Questions

Does a DEXA scan hurt?

No. A DEXA scan is painless. You lie on a padded table while a scanner arm moves over your body. You will not feel anything during the scan. The only minor discomfort some people experience is lying still for 10 to 30 minutes, especially if you have arthritis or back pain.

How much radiation am I exposed to during a DEXA scan?

A DEXA scan uses very low-dose radiation — roughly one-tenth of a chest X-ray and about the same as the radiation you receive from the sun in one week. The benefit of knowing your bone density far outweighs the small radiation risk, and DEXA is considered safe even if repeated every year.

Can I have a DEXA scan if I am pregnant?

No. DEXA scans are not recommended during pregnancy because they use X-rays. If you need bone density testing and are pregnant or think you might be, tell your doctor. You can have the scan after your baby is born or after you finish breastfeeding, depending on your doctor's recommendation.

What if my DEXA results show osteoporosis but I have never broken a bone?

Osteoporosis means your bones are weaker than normal, but it does not mean you will definitely break a bone. Your doctor will calculate your 10-year fracture risk using your DEXA score, age, and other factors. This helps your doctor decide whether you need medication or whether lifestyle changes like exercise, calcium, and vitamin D are enough for now.

Can I eat or drink before my DEXA scan?

Yes. You do not need to fast before a DEXA scan. You can eat, drink, and take your regular medications as usual. The only exception is calcium supplements — ask your doctor whether to skip them the morning of your scan, as some providers prefer this to avoid any possible interference with results.