DEXA Scan and T-Score Explained: How to Read Your Bone Density Results

A bone density test is the standard way to find out how strong your bones are before a fracture happens. The test is quick, painless, and uses very little radiation. The results, however, come as numbers and terms that can be confusing. Here is what they mean.

What Is a DEXA Scan?

DEXA (also written DXA) stands for dual-energy X-ray absorptiometry. You lie on a table while a scanner passes over your body, usually measuring the hip and lower spine, and sometimes the forearm. It compares how much X-ray energy your bones absorb to reference values, which tells doctors your bone mineral density.

How to Read a T-Score

A T-score compares your bone density with that of a healthy young adult of the same sex:

• -1.0 or higher: normal bone density
• Between -1.0 and -2.5: low bone mass, known as osteopenia
• -2.5 or lower: osteoporosis

The lower the number, the lower the density. A difference of one point represents a substantial change in fracture risk.

What Is a Z-Score?

A Z-score compares you with people of your own age and sex. It is typically used for premenopausal women, men under 50, and children. A very low Z-score can suggest that something other than normal aging, such as a medical condition or medication, is affecting bone, and it may prompt further tests.

Who Should Be Screened?

Many guidelines recommend a scan for all women at 65 and men at about 70, and earlier for people at higher risk, such as postmenopausal women with risk factors, anyone who has broken a bone from a minor fall after 50, and people on long-term steroids. Your doctor can tell you when you should start. Read more in our guide to risk factors and early signs.

How to Prepare

• Wear loose clothing without metal zippers or buttons.
• Ask whether to skip calcium supplements for 24 hours beforehand.
• Tell the technician about recent barium tests or nuclear scans.
• Inform them if you might be pregnant.

Beyond the T-Score: Fracture Risk

The T-score is only one piece of information. Doctors often combine it with the FRAX tool, which also considers age, previous fractures, family history, smoking, alcohol, steroid use, and body size to estimate your ten-year risk of a hip or major osteoporotic fracture. That estimate guides decisions about medication.

What Happens During the Appointment

Most people are surprised by how simple the process is. You arrive, change into a gown if needed, and lie on a padded table while a scanning arm passes over the hips and lower spine. Sometimes the forearm is scanned too. You will be asked to stay still, and the scan itself takes around 10 to 20 minutes. There are no injections, and you can usually resume normal activity right away.

The technician may ask about your height and weight, because height loss can be a clue to spinal fractures. A report is then sent to your doctor, who will explain what it means for you.

Common Reasons Results Can Look Different

If you have had scans in different places, the numbers may not match exactly. Several things can cause this:

• Different machines: models and calibration vary between facilities.
• Arthritis or spinal changes: degenerative changes in the lower spine can make density look higher than it truly is.
• Previous surgery or implants: metal and certain procedures can interfere with readings.
• Positioning: small differences in how you are placed can change results slightly.
• Normal variation: a very small change between scans may not be meaningful.

That is why doctors look at trends over time using the same machine whenever possible.

What Happens After an Abnormal Result?

A low score is not a sentence. Your doctor will usually consider your whole risk picture, and the next steps may include:

1. Blood tests to check vitamin D, calcium, thyroid, kidney function, and sometimes other markers.
2. A review of your medicines and any conditions that can affect bone.
3. A FRAX fracture-risk estimate to guide decisions about treatment.
4. Advice on nutrition, exercise, and fall prevention.
5. A discussion of prescription medicine if your risk is high.

Our guides to osteopenia and improving bone density after 60 cover what often comes next.

Questions About DEXA Scans

• Is the radiation dangerous? The dose is very low, typically much less than a standard chest X-ray in many cases.
• Can men be tested? Yes. Men can have osteoporosis too, and guidelines suggest screening around age 70, earlier with risk factors.
• Should I stop my supplements before the test? Many facilities ask you to skip calcium supplements for 24 hours. Follow their instructions.
• Are there alternatives? Some clinics use ultrasound screening of the heel, but DEXA remains the standard for diagnosis.

Which Site Is Used for Diagnosis?

A DEXA report usually lists results for several regions, such as the lumbar spine, total hip, and femoral neck. For diagnosis, doctors generally use the lowest T-score from these standard sites. In some cases, such as in people with severe arthritis of the spine, hyperparathyroidism, or very high body weight, the forearm may also be scanned. Your report may include a color-coded graph that shows where each reading falls relative to the normal range.

If different sites give different results, do not be alarmed. It is common for the hip and spine to differ because they contain different mixtures of dense outer bone and spongy inner bone, and they respond differently to age, hormones, and activity.

Other Tests You May Hear About

• Vertebral fracture assessment (VFA): a low-dose imaging add-on that can detect spinal fractures that were never noticed.
• Trabecular bone score (TBS): software that analyzes the texture of the spine image and can improve fracture-risk estimates.
• Bone turnover markers: blood or urine tests that show how quickly bone is being broken down and rebuilt.
• Quantitative CT: a three-dimensional measurement used in specific situations.
• Heel ultrasound: a screening tool that is not used to diagnose osteoporosis.

Getting the Most From Your Appointment

Bring your previous scan reports and a list of your medicines and supplements. Ask your doctor to explain which site gave your lowest score, what your FRAX estimate is, and when to repeat the test. If you are concerned about cost, ask whether your insurance covers the scan and at what interval. Keeping a personal record of every scan makes it easier to see trends over time.

To learn what you can do between scans, read osteopenia explained and our guide to natural ways to increase bone density.

Key Takeaways

• T-scores of -1.0 or higher are normal, -1.0 to -2.5 is osteopenia, and -2.5 or lower is osteoporosis.
• The lowest result across standard sites is typically used for diagnosis.
• FRAX adds history and risk factors to the numbers.
• Use the same facility for repeat scans when possible.

More Questions, Answered

Can I eat or drink before a DEXA scan?

In most cases, yes. You can usually eat normally, but follow the instructions from your imaging center, particularly about calcium supplements.

Does a normal T-score mean I will never get osteoporosis?

No. Bone loss continues with age, so a normal result today is reassuring but does not guarantee future results. Your doctor will advise when to repeat the test.

Is a DEXA scan the same as an ordinary X-ray?

They both use X-rays, but DEXA uses two energy levels and a lower dose to measure bone mineral density. A standard X-ray cannot reliably detect early bone loss.

Can I compare scans from different clinics?

It is better to use the same machine whenever you can. If you must change facilities, ask that the earlier images or data be shared so the new technician can compare them correctly.

How Often Should the Scan Be Repeated?

Follow-up is commonly every one to two years if you have started treatment or have significant bone loss, and less often if results are normal. Because machines vary, it is best to use the same facility each time. Lifestyle changes such as regular, appropriate exercise and good nutrition are discussed alongside these results.

This article is for general education only and is not medical advice. Talk with your doctor or another qualified healthcare professional before changing your diet, exercise routine, supplements, or medications.