DEXA Scan: What It Measures, Cost, Preparation & How to Read Results

What a DEXA Scan Measures

• Bone mineral density (BMD): Measured in g/cm² at the lumbar spine, femoral neck, total hip, and sometimes the distal radius. Results are reported as T-scores and Z-scores.
• T-score: Compares your BMD to the average BMD of a healthy 30-year-old. T-score of 0 = average peak bone mass. Each -1.0 increment represents ~10-12% lower bone density and approximately doubles fracture risk.
• Z-score: Compares your BMD to the average for your age and sex. A Z-score below -2.0 suggests bone loss beyond normal aging and warrants investigation for secondary causes.
• Body composition (optional): Total body DEXA measures lean mass, fat mass, bone mineral content, and visceral adipose tissue (VAT) with research-grade accuracy. This is increasingly used for fitness assessments and metabolic risk evaluation.

How to Prepare

• Clothing: Wear loose, comfortable clothing without metal zippers, buttons, or underwire. You may be asked to change into a gown.
• Calcium supplements: Stop calcium supplements 24 hours before the scan — calcium tablets in the GI tract can falsely elevate spine BMD readings.
• Contrast agents: Wait at least 7 days after any barium or gadolinium contrast study before a DEXA scan.
• No fasting required.
• Remove metal: Belt buckles, jewelry near scan sites, and metal clasps should be removed.
• Consistency: For follow-up scans, use the same machine and facility when possible. BMD values vary between manufacturers, so trending requires consistent equipment.

Cost and Insurance Coverage

Average cost: $150-$400 without insurance. Medicare covers a bone density test every 2 years for women 65+ and for certain high-risk individuals. Most private insurance covers DEXA when ordered for appropriate indications (postmenopausal, risk factors, fracture history, long-term corticosteroid use).

Medicare coverage: Covered every 24 months for women 65+, estrogen-deficient women at risk, individuals with vertebral abnormalities, those on long-term glucocorticoid therapy, and patients with primary hyperparathyroidism. A physician order is required.

Body composition DEXA: Typically $75-$200 and is usually self-pay/cash. Insurance generally does not cover DEXA when ordered solely for body composition assessment.

How to Interpret Your Results

Key points: The spine T-score can be falsely elevated by degenerative changes (arthritis, disc disease) in patients over 65, which is why the hip is often more reliable in older adults. Compare results at the same site over time — spine-to-spine, hip-to-hip. A change of 3-5% between scans is needed to be clinically significant (exceeds the scanner's precision error).

How Often Should Menopausal Women Get a DEXA Scan?

There isn't one fixed rescreening interval that fits every menopausal woman — the right schedule depends on age and individual risk factors more than on menopause status alone. The Bone Health & Osteoporosis Foundation and USPSTF screening guidance generally frame it this way:

• Average-risk women: Routine screening is generally recommended starting at age 65, per USPSTF guidance for postmenopausal women without additional risk factors.
• Postmenopausal women under 65 with risk factors: Earlier baseline screening is generally appropriate with risk factors such as early or surgical menopause, a family history of osteoporosis or hip fracture, low body weight, a prior fragility fracture, long-term corticosteroid use, or a condition known to affect bone (celiac disease, hyperthyroidism, and similar). Many clinicians order a baseline scan around the start of menopause itself when these factors are present, rather than waiting until 65.
• Rescreening after a normal baseline: A repeat scan every 2 years — the interval Medicare covers — is a common and reasonable default for women with a normal T-score and no new risk factors, though some clinicians extend the interval further after a strongly normal baseline, since bone density changes slowly over short periods.
• Rescreening if the baseline shows osteopenia: Women whose first scan already shows osteopenia are generally kept on a more consistent roughly 2-year recheck schedule, with less room to extend it, since they have less bone reserve before crossing into the osteoporosis range.

These are general screening-interval principles, not a substitute for individualized guidance — the right interval for you should be set with your doctor based on your specific risk factors, prior results, and whether you're already on treatment that itself needs monitoring. For why risk rises so sharply at this life stage, see bone density and menopause.

DEXA vs. Other Bone and Body Composition Methods

DEXA is not the only way to estimate bone or body composition, but it remains the reference standard for a specific reason: it directly measures how much X-ray energy bone absorbs, rather than estimating density from an indirect signal.

• Quantitative ultrasound (heel scan): Common at health fairs and pharmacies. It estimates bone quality through sound-wave transmission, not true density, and works only as a screening tool to flag who needs a real DEXA scan, not to diagnose osteoporosis on its own.
• Quantitative CT (QCT): Measures true 3D bone density and can detect changes DEXA might miss in patients with spinal arthritis, but it involves far more radiation and is reserved for specific clinical situations.
• Bioelectrical impedance (BIA/InBody): Estimates body composition by running a small current through tissue and inferring fat and muscle from resistance. It is convenient and radiation-free but noticeably less accurate than DEXA for body composition, and it does not measure bone density at all. See our DEXA vs InBody comparison for the accuracy gap in more detail.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases lists DEXA as the standard diagnostic tool precisely because the other methods above are screening or estimation tools, not diagnostic-grade measurements accepted for a formal osteoporosis diagnosis.