What Is a DXA Scan?

A DXA (also known as DEXA) scan is short for dual-energy X-ray absorptiometry. It is a simple, low-dose imaging test that measures bone density. It can spot early signs of bone loss and help doctors act before fractures happen. Doctors consider the scan one of the most accurate ways to measure bone density, especially in the hips and spine, where fractures are most common.

If you have questions about bone density testing and what the scan results may mean for your long-term health, Allison J. Hahr, MD, an endocrinologist at Northwestern Medicine, offers insight.

“DXA scans are the gold standard for measuring bone density to diagnose osteoporosis and identify those at higher fracture risk,” says Dr. Hahr. “The test is quick, and the radiation dose is very low compared to an X-ray.”

Who Should Consider Getting a DXA Scan?

DXA scans are commonly recommended for women age 65 and older and men age 70 and older. However, earlier testing may help people with certain risk factors that increase the likelihood of bone loss.

These risk factors may include:

• Family history of weak bones or osteoporosis
• Early menopause or low estrogen levels
• Long‑term use of steroids or certain medications
• Low body weight
• Smoking or heavy alcohol use
• Chronic health conditions that affect bone strength

“We recommend screening earlier than the recommended age to identify individuals who may be at higher fracture risk,” says Dr. Hahr. “In addition to the above risk factors, we also recommend earlier screening for those who have had a low-trauma fracture as an adult — such as a fall from standing height or less — or those who have a known condition associated with bone loss.”

Early detection of osteoporosis or increased fracture risk can lead to earlier intervention, she adds.

What Is the Scan Experience Like?

A DXA scan is quick, painless and noninvasive. Most scans take 10 to 20 minutes. Patients lie still on a table while an open scanner passes over the body. The test does not require injections, needles or contrast dye, which some imaging exams use.

Patients are usually advised to wear loose, comfortable clothing and avoid clothing with metal zippers, buttons or belts. In some cases, doctors may recommend stopping a calcium supplement for 24 hours before the scan to prevent interference with results. Otherwise, the test requires little preparation.

Is Radiation Exposure a Concern?

DXA scans use a very small amount of radiation — much less than a standard chest X‑ray. For most people, the exposure is minimal and considered safe. The benefits of identifying bone loss early and preventing fractures generally outweigh the risks.

How Are the Results Reported?

DXA scan results measure bone mineral density (BMD) and are most often reported using T-scores and Z-scores. These scores show how your bone density compares to reference groups.

• T-score: Compares your bone density with that of a healthy young adult of the same sex
• Z-score: Compares your bone density with that of people your age and sex

A physician reviews the scores and explains what they mean for bone strength and fracture risk. Results typically fall into one of three categories:

• Normal bone density: Bone mass falls within the expected range
• Osteopenia: Mild bone loss that may increase fracture risk
• Osteoporosis: More significant bone loss and a higher risk of fractures

Even mild bone loss found early can guide prevention strategies and reduce the risk of future fractures.

What Happens if Bone Loss Is Found?

If a DXA scan shows bone loss, the next steps depend on age, overall health and fracture risk. Some people may benefit from lifestyle changes, such as strength training, weight‑bearing exercise and improved nutrition. These habits can help slow bone loss and support bone strength.

Diet also plays an important role. Getting enough calcium and vitamin D — through food, supplements or both — helps maintain healthy bones. A physician can help determine whether supplements or additional treatment are appropriate based on individual needs. In some cases, medication may be prescribed to slow bone loss or lower fracture risk.

Good food sources of calcium include:

• Dairy products
• Calcium-fortified orange juice or cereals
• Tofu made with calcium sulfate
• Canned salmon with bones
• Almonds
• Dried figs
• Broccoli, kale and collard greens

Good food sources of vitamin D include:

• Vitamin D-fortified milk, yogurt, plant-based milks, orange juice and cereals
• Cod liver oil
• Canned salmon, tuna and sardines
• Fresh shiitake mushrooms
• Egg yolks
• Cheese
• Beef liver

“Preventing bone loss and reducing fracture risk can be achieved through a combination of nutrition, exercise and healthy habits,” says Dr. Hahr. “Avoiding smoking, limiting alcohol, eating adequate protein (without excess intake) and exercising regularly also help reduce your risk.” 

Maintaining balance and muscle strength is also important for fall prevention and lowering your risk of fractures, she adds. In some cases, medications may be needed to reduce the risk of future bone loss and fractures.

How Often Should a DXA Scan Be Repeated?

Some patients who are at higher risk may need to repeat a bone density scan every one to two years, although timing varies. People with normal bone density often need less frequent testing, while those with osteoporosis or multiple risk factors usually need closer monitoring.

Repeat scans help clinicians track changes over time and evaluate whether treatment is working.

Protecting Bone Health Before Problems Start

Bone loss often occurs quietly, without symptoms. A DXA scan offers insight before fractures happen. Understanding personal risk factors, staying active and following screening recommendations can make a meaningful difference in your long‑term bone health.

“DXA scans are a simple and straightforward screening tool that helps identify those at increased fracture risk,” says Dr. Hahr. “Bone loss and osteoporosis do not cause pain unless a fracture is present. Getting a DXA scan is an investment in your long-term bone health.”