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 check for osteoporosis. It takes pictures of your bones using very low-dose X-rays — less radiation than a chest X-ray — and compares your bone density to that of a healthy young adult. The scan takes about 10 to 30 minutes and is painless. You lie on a table while the machine passes over your hip, spine, and sometimes your forearm.
Your doctor will order a DEXA scan if you are at risk for bone loss. Risk factors include being over 50, having a family history of osteoporosis, taking certain medications like corticosteroids, or having conditions that affect bone health. Men over 70 and all women over 65 should have at least one scan, even without symptoms.
The scan produces a score called a T-score, which tells you how your bones compare to a healthy 30-year-old's bones. A T-score of −1.0 or higher is normal. A score between −1.0 and −2.5 means you have low bone density (sometimes called osteopenia). A score below −2.5 means you have osteoporosis.
Key Takeaways
- A DEXA scan is a painless X-ray test that measures bone density and takes 10 to 30 minutes.
- Your doctor will recommend a scan if you are over 50 with risk factors, or over 65 or 70 depending on your sex.
- The T-score from your scan tells you whether your bones are normal, have low density, or have osteoporosis.
- You do not need to fast or prepare for a DEXA scan, but you should wear loose clothing and remove metal objects.
- If your first scan shows low bone density, your doctor may order follow-up scans every one to two years to track changes.
Who should get tested and when
The U.S. Preventive Services Task Force recommends bone density screening for all women age 65 and older and all men age 70 and older. Women between 50 and 64 and men between 50 and 69 should be screened if they have risk factors — such as low body weight, a parent who broke a hip, smoking, heavy alcohol use, or rheumatoid arthritis.
If you have already had one DEXA scan, your doctor will decide how often you need another based on your results and your risk. People with normal bone density may not need another scan for 10 years. People with low bone density typically have a follow-up scan every one to two years to see if bone loss is continuing or if treatment is working.
Talk to your doctor about whether you should be tested. Bring up any broken bones you have had as an adult, any medications you take regularly, and whether anyone in your family has had osteoporosis or broken bones.
What happens before and during the scan
You do not need to fast or do anything special to prepare for a DEXA scan. Wear loose, comfortable clothing without metal zippers, buttons, or snaps — the technician may ask you to change into a hospital gown. Remove jewelry, watches, and any metal objects from your pockets.
During the scan, you will lie on your back on a padded table. The technician will position your legs and arms in a specific way to keep them still. A large arm will move slowly over your body, taking pictures. You will feel nothing — there is no pain, heat, or noise. You can breathe normally and talk to the technician if you need to.
If you are pregnant or think you might be, tell the technician before the scan. DEXA scans use very little radiation, but pregnancy is still a reason to postpone the test. If you have had a recent CT scan or nuclear medicine scan with contrast dye, tell your doctor — you may need to wait a few days before your DEXA scan.
Understanding your DEXA scan results
Your results will include a T-score for each bone area scanned (hip, spine, and sometimes forearm). The T-score is a number that compares your bone density to that of a healthy 30-year-old. A higher T-score means stronger bones.
Here is what the scores mean:
| T-Score Range | What It Means |
|---|---|
| −1.0 or higher | Normal bone density |
| −1.0 to −2.5 | Low bone density (osteopenia) |
| Below −2.5 | Osteoporosis |
| Below −2.5 plus a broken bone | Severe osteoporosis |
Your doctor will also calculate your 10-year fracture risk using a tool called FRAX, which combines your T-score with other factors like age, weight, smoking status, and alcohol use. This helps your doctor decide whether you need treatment to prevent breaks.
Other tests your doctor might order
In some cases, your doctor may order additional tests to understand why your bones are weak or to rule out other conditions. A blood test can check your calcium, vitamin D, and thyroid levels — all of which affect bone health. Your doctor may also test your kidney function if you are considering osteoporosis medication.
If you have had a broken bone and your doctor suspects osteoporosis, an X-ray of the broken bone may be ordered first. X-rays cannot detect early bone loss the way a DEXA scan can, but they can show a break and help rule out other causes.
A newer test called a high-resolution peripheral quantitative CT scan (HR-pQCT) can look at bone structure in more detail, but it is not routine and is usually done only in research settings or for specific medical questions.
What to do after your scan
Your doctor will review your results with you and explain what they mean for your bone health. If your scan shows normal bone density, your doctor will likely recommend you continue healthy habits: get enough calcium and vitamin D, exercise regularly, avoid smoking, and limit alcohol. You may not need another scan for many years.
If your scan shows low bone density or osteoporosis, your doctor may recommend medication, dietary changes, or both. Common medications include bisphosphonates (such as alendronate), which slow bone loss. Your doctor will also check your vitamin D level and may recommend a supplement if it is low.
Ask your doctor for a copy of your scan results and your T-score. Keep these records so you and your doctor can compare future scans and track whether your bone density is stable, improving, or continuing to decline.
Frequently Asked Questions
Does a DEXA scan hurt?
No. A DEXA scan is painless. You lie still on a table while the machine takes pictures. You will not feel heat, cold, or any sensation. The entire process takes 10 to 30 minutes.
How much radiation does a DEXA scan use?
A DEXA scan uses very little radiation — about one-tenth the dose of a chest X-ray. The benefit of knowing your bone density far outweighs the small radiation risk, especially for people over 50.
What if my results show osteoporosis?
Osteoporosis means your bones are weaker and more likely to break, but it does not mean you will definitely break a bone. Your doctor will talk with you about your fracture risk and may recommend medication, calcium and vitamin D, weight-bearing exercise, and fall prevention steps to protect your bones.
Can I get a DEXA scan if I am overweight?
Yes. DEXA scans work for people of all body sizes. Extra weight can sometimes make bones appear denser on the scan, but your doctor knows how to interpret results for your body type. Tell the technician your height and weight so they can position you correctly.
How often do I need a DEXA scan?
If your bones are normal, you may not need another scan for 10 years. If you have low bone density or osteoporosis, your doctor will usually recommend a follow-up scan every one to two years to track changes and see if treatment is working.