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.

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.