How to Read DEXA Scan Results: T-Scores and Z-Scores

Learn which bone-density score applies to you, what the number compares, and why the result is only one part of your bone-health assessment.

Medically Reviewed By: Rhonda Collins, FNP-C | September 11, 2026 | 6 min read

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Your DEXA or DXA report usually shows bone mineral density (BMD) alongside a T-score, a Z-score, or both. Start with the score intended for your age and life stage. Then check which bone was measured. The number is a comparison with a reference population, not a complete verdict on fracture risk or treatment.

What does a DEXA scan measure?

A bone-density DEXA scan measures how much mineral, such as calcium, is in a specific area of bone and reports it as BMD. DXA and DEXA are two names for dual-energy X-ray absorptiometry. The test is non-invasive and painless and uses very little radiation. Clinicians use it to identify osteoporosis before a fracture occurs, estimate future fracture risk, and monitor treatment. The Bone Health and Osteoporosis Foundation explains the test and its uses. RadiologyInfo also describes the scan’s low-dose, non-invasive technique.

Some DEXA scans also report body fat, lean mass, and other body-composition measurements. Those values answer a different question from the bone-density scores. Read Mito’s broader guide to DEXA and body composition for that side of the report.

What is the difference between a T-score and a Z-score?

A T-score compares your BMD with the average BMD of a healthy young-adult reference population. A Z-score compares your BMD with the average for people of the same age and sex. Where adequate reference data exist, the International Society for Clinical Densitometry (ISCD) recommends that Z-scores use population-specific data based on self-reported ethnicity. NIH NIAMS explains the two comparisons, and the ISCD states its reference-data convention.

Both scores are expressed in standard deviations from the applicable reference mean. A score of 0 is at that mean. A negative score is below it. The lower the number, the farther the measured BMD is below the reference mean.

Which bone-density score should you use?

• Postmenopausal women and men age 50 and older: T-scores are preferred for diagnostic classification.
• Females before menopause and males younger than 50: Z-scores, not T-scores, are preferred.
• Children: Z-scores are also used, but pediatric results need age-appropriate clinical interpretation.

These score-selection conventions come from the ISCD Adult Official Positions. If your report includes both scores, use the one that fits the applicable group instead of choosing whichever number looks better or worse.

What does your T-score mean?

For postmenopausal women and men age 50 and older, the T-score categories below apply to diagnostic classification. These cutoffs come from the Bone Health and Osteoporosis Foundation and should not be applied to younger adults.

The category is not the whole diagnosis or fracture-risk assessment. The ISCD distinguishes BMD classification from fracture-risk assessment and notes that people with low bone mass are not necessarily at high fracture risk. A prior fracture can also change the clinical interpretation even when the T-score is above the osteoporosis cutoff. The ISCD explains these distinctions, and the Bone Health and Osteoporosis Foundation describes how fracture history affects diagnosis.

What does your Z-score mean?

For females before menopause and males younger than 50, use the Z-score language established by the ISCD:

A Z-score is a comparison, not an osteoporosis diagnosis by itself. The ISCD specifically states that osteoporosis cannot be diagnosed in men under 50 from BMD alone. A clinician needs to interpret a younger adult’s result with medical history, risk factors, and other findings rather than applying the older-adult T-score categories.

How do you read a DEXA report step by step?

Read a DEXA bone-density report in this order:

1. Find the measured site. A report may list the lumbar spine, total hip, femoral neck, or forearm separately. Do not assume scores from different sites mean the same thing.
2. Choose the applicable score. Use T-scores for postmenopausal women and men age 50 and older. Use Z-scores for females before menopause and males younger than 50.
3. Apply the right interpretation. Match a T-score only with the qualified older-adult categories, or match a Z-score with the expected range for age.
4. Check the report’s impression. The interpreting clinician may identify technical limitations, excluded areas, or a conclusion that is not obvious from one row of numbers.
5. Put changes in context. Compare repeat scans only when the site and methods are comparable. A small numerical difference may fall within the facility’s measurement precision rather than represent a real biological change.
6. Review the complete picture with your clinician. Fracture history, age, medicines, health conditions, family history, fall risk, and other clinical information can change what the result means for you.

The ISCD recommends that follow-up reports identify the prior study and measured region used for comparison and account for the facility’s least significant change, a threshold based on its measurement precision. It also separates BMD classification from fracture-risk assessment. See the ISCD reporting and follow-up positions.

Why can different parts of the report show different scores?

DEXA reports can show a different BMD and score for each measured site because bone density is not uniform across the skeleton. Positioning, artifacts, structural changes, and the reference database can also affect a result. The ISCD provides site-specific rules for which spine, hip, and forearm measurements can support diagnostic classification. Review the ISCD site and reporting standards.

Do not average scores yourself or select one site without the report’s clinical interpretation. Ask which measured site determined the impression, whether every site was technically valid, and whether the scan can be compared reliably with an earlier study.

What should you discuss after a bone-density result?

Bring the full report and any earlier scans to the clinician who ordered the test. Ask:

• Which score and measured site apply to me?
• Does my fracture history or another risk factor change the interpretation?
• Is any difference from my prior scan larger than the facility’s measurement error?
• Could a medicine or health condition contribute to the result?
• Would the result change follow-up timing or management?

NIH NIAMS recommends reviewing BMD results with a doctor because diagnosis and treatment decisions use the scan together with age and other fracture-risk factors. Read the NIH NIAMS follow-up guidance.

Mito offers a non-diagnostic body-composition DEXA scan through BodySpec partner locations in California, Colorado, Illinois, Massachusetts, Texas, and Washington. Availability is limited to those states. The scan is offered at our cost. BodySpec’s whole-body bone-density score is a general bone-health reference and cannot determine whether you have osteoporosis. If you need an osteoporosis evaluation, ask your clinician about a diagnostic bone-density examination. The product page owns current availability and ordering details.