The standard test for osteoporosis is a DXA scan (sometimes written DEXA), a low-dose X-ray that measures the mineral density of your bones. The scan is quick, painless, and typically takes 10 to 30 minutes. But DXA isn’t the only tool doctors use. Depending on your age, risk factors, and symptoms, testing for osteoporosis can also involve blood work, fracture risk calculators, and in some cases, alternative imaging.
The DXA Scan: How It Works
A DXA scan measures calcium and other minerals in your bones by passing two low-energy X-ray beams through them. The difference in how the two beams are absorbed tells the machine how dense your bone tissue is. You lie on a padded table while an arm passes slowly over your hips and lower spine, the two sites where osteoporotic fractures cause the most damage. Some scans also include the wrist or forearm.
The radiation exposure is extremely low, far less than a standard chest X-ray. You stay fully clothed as long as your clothing doesn’t have metal zippers, belts, or buttons. If it does, you’ll change into a gown. Leave jewelry at home. The one preparation step that matters: stop taking calcium supplements at least 24 hours before the test, since undigested calcium in your system can throw off the reading.
What Your T-Score Means
Your DXA results come back as a T-score, which compares your bone density to that of a healthy 30-year-old (the age when bones are at peak strength). The World Health Organization sets the thresholds:
- T-score of -1.0 or higher: Normal, healthy bone density.
- T-score between -1.0 and -2.5: Osteopenia, meaning your bones are thinner than normal but not yet in the osteoporosis range.
- T-score of -2.5 or lower: Osteoporosis.
A T-score of -2.5 doesn’t mean your bones are about to break. It means your fracture risk is significantly elevated compared to someone with normal density. The further below -2.5 your score falls, the higher that risk climbs. Your doctor may also mention a Z-score, which compares you to others your own age and sex. An unusually low Z-score can signal that something besides normal aging is driving your bone loss, prompting further investigation.
Who Should Get Tested
The U.S. Preventive Services Task Force recommends routine osteoporosis screening for all women aged 65 and older. For postmenopausal women younger than 65, screening is recommended if you have one or more risk factors that increase your chance of fracture. Those risk factors include a parent who fractured a hip, long-term use of steroid medications like prednisone, low body weight, current smoking, and heavy alcohol use (three or more drinks a day).
For men, there’s no universal screening recommendation yet. The Task Force says there isn’t enough evidence to determine the benefits and harms of routine screening in men. That said, men with clear risk factors, such as long-term steroid use, a history of fractures from minor falls, or conditions like rheumatoid arthritis, are often tested on a case-by-case basis.
The FRAX Tool: Estimating Fracture Risk
A T-score alone doesn’t capture the full picture. The FRAX calculator, developed by the World Health Organization, estimates your 10-year probability of a major osteoporotic fracture by combining your bone density with several other variables: age, sex, BMI, whether you’ve had a previous fracture, whether a parent fractured a hip, current smoking status, steroid use, rheumatoid arthritis, secondary osteoporosis, and alcohol intake of three or more units per day.
FRAX is especially useful when your T-score falls in the osteopenia range (between -1.0 and -2.5), where the decision about whether to start treatment isn’t clear-cut. A high FRAX score can tip the balance toward treatment even if your T-score hasn’t crossed the -2.5 threshold. Your doctor typically runs this calculation using your DXA results, so you won’t need to do anything extra.
Blood and Urine Tests
A DXA scan tells you how dense your bones are right now. It doesn’t tell you why they’re losing density or how fast. That’s where lab work comes in. Blood tests can check your vitamin D levels, calcium, thyroid function, and parathyroid hormone, all of which directly affect bone health. Low vitamin D or an overactive parathyroid gland, for example, can silently drain minerals from your skeleton for years.
Doctors can also measure bone turnover markers, proteins released into your blood and urine that reflect how quickly bone is being broken down and rebuilt. If these markers are significantly elevated (more than three times the normal range), that’s a red flag for conditions beyond typical osteoporosis: hyperparathyroidism, thyroid disorders, kidney disease, Paget disease, or even cancer. These tests are also used to track whether osteoporosis treatment is working, since changes in turnover markers show up months before a follow-up DXA scan would detect any difference in density.
Heel Ultrasound and Other Peripheral Tests
You may encounter bone density screening at a health fair or pharmacy that uses ultrasound on your heel. These portable devices are painless and fast, but they have real limitations. Heel ultrasound catches about 53% of people who actually have osteoporosis, meaning it misses nearly half of true cases. Its strength is the other direction: a negative result correctly rules out osteoporosis about 82% of the time.
Large studies have found that heel ultrasound can predict hip fracture risk about as well as DXA in postmenopausal women over 65. The problem is that there are no established treatment guidelines based on ultrasound scores alone, and the test can’t reliably track changes in bone density over time. So if your heel ultrasound comes back abnormal, you’ll still need a full DXA scan to confirm the diagnosis and establish a baseline for monitoring. Think of peripheral tests as a useful first alert, not a replacement for DXA.
QCT Scans: A 3D Alternative
Quantitative computed tomography, or QCT, uses a standard CT scanner to measure bone density in three dimensions rather than the flat, two-dimensional image a DXA produces. This gives it a distinct advantage at the spine, where it can isolate the spongy interior bone (trabecular bone) that deteriorates first in osteoporosis, without interference from arthritis or calcified blood vessels that can falsely inflate DXA readings.
QCT involves more radiation than DXA and costs more, so it’s not the first-line test for most people. It’s most useful when DXA results are unreliable, for instance in people with severe arthritis in the spine, or when a CT scan is already being done for another reason and bone density can be assessed from the same images. This “opportunistic” screening is gaining traction as a way to catch osteoporosis in people who might never get a standalone DXA.
Insurance and How Often to Test
Medicare covers a bone density test once every 24 months if you meet certain criteria: you’re a woman determined to be estrogen-deficient and at risk, your X-rays suggest bone loss or vertebral fractures, you’re taking or about to start steroid medications, you’ve been diagnosed with primary hyperparathyroidism, or you’re being monitored on osteoporosis treatment. More frequent testing is covered when deemed medically necessary.
Most private insurers follow similar rules, covering screening DXA scans for women 65 and older and for younger patients with documented risk factors. If you’re unsure about your coverage, call your insurance before scheduling. The out-of-pocket cost for a DXA scan without insurance typically ranges from $100 to $300, depending on the facility and your location.