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

A DEXA scan (dual-energy X-ray absorptiometry) is the most common way doctors measure bone density. It uses two X-ray beams at different energy levels to calculate how much mineral is packed into your bones. The scan takes about 10 to 30 minutes and involves lying still on a table while a scanner arm moves over your hip, spine, and sometimes your forearm.

DEXA scans are painless, use very low radiation (less than a standard chest X-ray), and give results the same day or within a few days. The test produces a score called a T-score, which compares your bone density to that of a healthy 30-year-old. A T-score of −1.0 or higher is considered normal bone density. A score between −1.0 and −2.5 indicates low bone density (sometimes called osteopenia). A score of −2.5 or lower means osteoporosis.

Key Takeaways

  • DEXA scans are the standard test for bone density and take 10 to 30 minutes with no pain or significant radiation exposure.
  • Your doctor may recommend screening based on age, sex, personal fracture history, or family history of osteoporosis.
  • A T-score of −2.5 or lower indicates osteoporosis; scores between −1.0 and −2.5 indicate low bone density.
  • Other imaging tests like CT scans or ultrasound can measure bone density but are used less often than DEXA.
  • Blood and urine tests do not diagnose osteoporosis but can show how quickly your bones are breaking down.

Who should get screened and when

The U.S. Preventive Services Task Force recommends bone density screening for all women age 65 and older, and for postmenopausal women under 65 who have risk factors. Men age 70 and older should also be screened. Younger adults of any sex may be tested if they have had a fracture from a minor fall or bump, a family history of osteoporosis, or conditions that affect bone health (such as rheumatoid arthritis or celiac disease).

Your doctor may also recommend screening if you take certain medications long-term, such as corticosteroids, or if you have had cancer treatment. The timing of repeat scans varies—some people need them every one to two years, while others may go longer between tests depending on their initial results and risk factors.

What happens during a DEXA scan

You will be asked to lie on your back on a padded table. The technician may place a pillow under your knees to keep your spine in a neutral position. You need to stay still while the scanner arm passes over the areas being measured, usually your lower spine and hip. You can wear regular clothes as long as they have no metal zippers, snaps, or buttons.

The scan itself is quiet and you will feel nothing. The technician may step out of the room or stay nearby. If you are pregnant or think you might be, tell the technician before the scan begins—DEXA uses radiation, though the dose is very small. After the scan, you can return to your normal activities immediately.

Understanding your T-score and what it means

Your DEXA results come back as a T-score and sometimes a Z-score. The T-score compares your bones to a healthy young adult's bones. The Z-score compares your bones to others your age and sex. Doctors focus on the T-score for diagnosis.

A T-score of −1.0 or above means normal bone density. Between −1.0 and −2.5 is low bone density (osteopenia), which means your bones are weaker than normal but you do not yet have osteoporosis. A T-score of −2.5 or lower means you have osteoporosis. The lower the score, the weaker your bones are and the higher your fracture risk. Your doctor will discuss what your specific score means for your health and whether treatment is needed.

Other imaging tests that measure bone density

DEXA is the standard, but other tests exist. Quantitative CT (QCT) uses a CT scanner to measure bone density in three dimensions rather than two. It can be more precise in some cases but uses more radiation than DEXA and costs more. Peripheral DEXA scans the forearm, heel, or finger instead of the hip and spine—these are faster and use less radiation but are less commonly used for diagnosis.

Ultrasound can estimate bone density by measuring how sound waves travel through bone, usually at the heel. It is quick and uses no radiation, but it is less accurate than DEXA and is not used to diagnose osteoporosis on its own. Your doctor will explain which test makes sense for your situation.

Blood and urine tests that show bone turnover

Blood and urine tests cannot diagnose osteoporosis, but they can show how fast your bones are breaking down and being rebuilt. These tests measure substances called bone turnover markers—proteins and minerals your body releases when bone is broken down. High levels suggest your bones are losing density faster than normal.

Common markers include P1NP (procollagen type 1 N-terminal propeptide) in blood and CTX (C-terminal telopeptide of type 1 collagen) in blood or urine. Your doctor may order these tests to understand your bone loss rate, to see how well a treatment is working, or to assess fracture risk beyond what the DEXA score alone shows. These tests are not routine screening—your doctor will order them only if there is a specific reason.

What to do before your bone density test

Most DEXA scans require no special preparation. You do not need to fast or stop taking medications. Wear comfortable, loose clothing without metal fasteners. Remove jewelry, belts, and anything else metal from the area being scanned. If you have had a barium X-ray or CT scan with contrast dye in the past week, tell your technician—these can interfere with DEXA results.

Bring your insurance card and photo ID. If you have had previous bone density scans at another facility, ask if those images can be sent to your current provider so your doctor can compare results over time. This comparison is often more useful than a single scan in deciding whether treatment is needed.

Frequently Asked Questions

Does a DEXA scan hurt?

No. DEXA scans are completely painless. You lie still on a table while a scanner arm moves over your bones. You will not feel anything during the test, and there are no needles or injections involved.

How much radiation does a DEXA scan use?

A DEXA scan uses about one-tenth the radiation of a chest X-ray. The dose is so low that the risk from radiation exposure is considered negligible. Pregnant women should avoid DEXA scans, but the radiation risk to others is minimal.

Can I get results the same day?

Results are usually available within a few days, though some facilities can provide preliminary results on the same day. Your doctor will review the results and discuss what they mean for your health and next steps.

What if my DEXA score shows low bone density but not osteoporosis?

Low bone density (osteopenia) means your bones are weaker than normal but you do not yet have osteoporosis. Your doctor may recommend lifestyle changes such as weight-bearing exercise and adequate calcium and vitamin D intake. Some people with low bone density also benefit from medication to slow bone loss.

How often do I need repeat bone density scans?

This depends on your initial results and risk factors. If your first scan is normal, you may not need another for 10 years or longer. If you have low bone density or osteoporosis, your doctor may recommend repeat scans every one to two years to track changes and see how treatment is working.