The main test: a bone density scan

The standard way to test for osteoporosis is a DEXA scan (dual-energy X-ray absorptiometry). It measures how much mineral is packed into your bones by taking two low-dose X-ray images of the same area. The scan itself takes 10 to 30 minutes and is painless — you lie still on a table while the machine passes over you.

A DEXA scan usually focuses on your hip and spine, the places where osteoporosis fractures happen most often. Some doctors also scan the forearm. The machine compares your bone density to that of a healthy 30-year-old adult and gives you a score called a T-score. That number tells your doctor whether your bones are normal, show early thinning (called osteopenia), or have osteoporosis.

DEXA is the test your doctor will order first. It is covered by Medicare at certain ages and intervals, and many private insurance plans cover it as well. If you do not have insurance, the cost varies widely by location and facility — anywhere from $100 to $300 out of pocket.

Key Takeaways

  • A DEXA scan is the standard test for osteoporosis and measures bone mineral density by taking two low-dose X-ray images of your hip and spine.
  • Your results come as a T-score, which compares your bone density to a healthy young adult and determines whether you have normal bones, osteopenia, or osteoporosis.
  • Medicare covers DEXA scans for women over 65, men over 70, and younger people with risk factors, though coverage rules vary by state.
  • A DEXA scan takes 10 to 30 minutes, requires no preparation, and exposes you to less radiation than a chest X-ray.
  • If DEXA results are unclear or you cannot have a DEXA scan, your doctor may order a different imaging test or blood work to assess bone health.

Who should get tested and when

Not everyone needs a bone density test. Your doctor will recommend one based on your age and risk factors. Medicare covers DEXA scans for women age 65 and older, men age 70 and older, and younger people of any age who have had a fracture from a minor fall or who have other risk factors (such as long-term steroid use, rheumatoid arthritis, or a family history of osteoporosis).

If you are a postmenopausal woman under 65, your doctor may recommend testing if you have risk factors. The same applies to men under 70. Your primary care doctor can review your personal and family history and tell you whether a test makes sense for you right now.

If you have already been tested and your results were normal, you typically do not need another scan for 1 to 2 years. If you have osteopenia or osteoporosis, your doctor will recommend repeat testing every 1 to 2 years to see whether your bone density is staying stable, improving, or getting worse.

What your T-score means

Your DEXA results come back as a T-score, which is a number that compares your bone density to that of a healthy 30-year-old. The score is measured in standard deviations — a way of showing how far your result is from the average.

A T-score of -1.0 or higher is considered normal bone density. A score between -1.0 and -2.5 means you have osteopenia, which is thinning bone that is not yet osteoporosis but does carry some fracture risk. A T-score of -2.5 or lower means you have osteoporosis. The lower the number, the weaker your bones are and the higher your fracture risk.

Your doctor will also look at a second number called the Z-score, which compares your bone density to others your age and sex. This helps your doctor understand whether your bone loss is normal for your age or faster than expected. If your Z-score is unusually low, your doctor may order additional tests to find out why — for instance, a thyroid problem or a vitamin D deficiency.

Preparation and what to expect on the day

A DEXA scan requires almost no preparation. You do not need to fast or stop taking medications. Wear loose, comfortable clothing without metal zippers, buttons, or snaps, because metal can interfere with the X-ray images. If you have had a recent CT scan or nuclear medicine scan using contrast dye, tell your doctor — you may need to wait a few days before your DEXA scan.

On the day of your scan, arrive 10 to 15 minutes early to check in. You will be asked to remove jewelry, glasses, and any metal objects from your pockets. You will then lie on your back on a padded table. The technician will position your legs and arms to keep them still and will leave the room while the scan runs. You will hear a faint buzzing sound as the machine moves over you. The whole appointment usually takes 30 minutes or less.

After the scan, you can go back to your normal activities right away. There are no side effects. Your doctor will review the images and your T-score and contact you with results, usually within a week.

Other tests your doctor might order

In most cases, a DEXA scan is all you need. But if your results are unclear, if you cannot have a DEXA scan for medical reasons, or if your doctor suspects a specific cause for bone loss, other tests may be ordered.

A quantitative CT scan (QCT) is a type of CT imaging that can measure bone density in three dimensions rather than two. It is more detailed than DEXA but uses more radiation and costs more. It is usually reserved for people with spine problems that make a standard DEXA hard to read, or for research studies.

Blood tests do not diagnose osteoporosis directly, but they can reveal causes of bone loss. Your doctor might check your vitamin D level, calcium level, thyroid function, or kidney function. If you are a woman, your doctor may also measure bone turnover markers — substances in your blood that show how fast your bones are breaking down and rebuilding. These markers can help predict fracture risk and track whether treatment is working.

Radiation exposure and safety

A DEXA scan uses X-rays, so you will receive a small amount of radiation. However, the dose is very low — about one-tenth the radiation of a chest X-ray and far less than a CT scan. For most people, the benefit of knowing your bone density far outweighs the small radiation risk.

If you are pregnant or think you might be, tell your doctor before the scan. DEXA scans are not recommended during pregnancy because of radiation exposure to the baby. If you have had multiple X-rays or CT scans recently, mention that to your doctor, though one additional DEXA scan will not cause harm.

The machine itself is safe and does not cause pain, burning, or any sensation at all. You are not injected with anything and do not go inside a closed space. If you are claustrophobic or have mobility issues, tell the technician — they can help you get comfortable on the table.

After your test: understanding your results and next steps

Your doctor will contact you with your results and explain what your T-score means for your bones. If your bones are normal, your doctor will discuss ways to keep them healthy — adequate calcium and vitamin D intake, weight-bearing exercise, and avoiding smoking and excess alcohol.

If you have osteopenia, your doctor may recommend the same lifestyle measures and may suggest repeat testing in 1 to 2 years to see whether your bone density is changing. Some people with osteopenia and high fracture risk may be offered medication to slow bone loss.

If you have osteoporosis, your doctor will likely recommend medication to strengthen your bones and reduce fracture risk. Common medications include bisphosphonates (such as alendronate), which slow bone loss, or other drugs that work differently. Your doctor will also discuss calcium and vitamin D supplements, exercise, and fall prevention. You will need repeat DEXA scans to track how well the treatment is working.

Frequently Asked Questions

Does a DEXA scan hurt?

No. A DEXA scan is painless. You lie on a padded table while the machine passes over you. You may hear a faint buzzing sound, but you will feel nothing. The entire scan takes 10 to 30 minutes.

Can I eat or drink before my DEXA scan?

Yes. There is no need to fast or change your diet before a DEXA scan. You can eat and drink normally and take all your regular medications. Just wear loose clothing without metal and arrive a few minutes early to check in.

How often do I need a bone density test?

If your bones are normal, you typically do not need another scan for 1 to 2 years. If you have osteopenia or osteoporosis, your doctor will usually recommend repeat testing every 1 to 2 years to track whether your bone density is stable or changing. Your doctor will tell you the right timing for you.

What if my DEXA results show I have osteoporosis?

Your doctor will discuss treatment options, which usually include medication, calcium and vitamin D supplements, weight-bearing exercise, and fall prevention strategies. Repeat DEXA scans will track how well treatment is working. Many people with osteoporosis can slow or stop bone loss with the right care.

Is a DEXA scan covered by insurance?

Medicare covers DEXA scans for women 65 and older, men 70 and older, and younger people with risk factors. Many private insurance plans also cover it. Coverage varies by plan and state. Call your insurance company or ask your doctor's office to check your coverage before your appointment.