Enter the scores from your bone density scan (DEXA/DXA) to understand what they mean.
This tool is for educational purposes only and does not replace a clinical evaluation. Always discuss your DXA results with your physician. WHO criteria apply to postmenopausal women and men age 50 and older. For premenopausal women, men under 50, and children, Z-scores are the preferred measure.
WHO Classification
Normal
T-Score Entered
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Standard Deviations
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Skeletal Site
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Score Used for Dx
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Where You Fall on the Bone Density Scale
-4.0 (Severe)-2.5-1.0+2.0 (High)
Z-Score Interpretation
Clinical Context
Understanding DXA Bone Density Scores
A DXA (dual-energy X-ray absorptiometry) scan measures bone mineral density at key skeletal sites. The results are reported as two scores: a T-score and a Z-score. Both compare your bone density to a reference population, but the reference group differs.
The T-score compares your bone mineral density to the peak bone mass of a healthy 30-year-old adult of the same sex. It is the score used by the World Health Organization to classify bone density as normal, osteopenia, or osteoporosis. T-scores are the primary diagnostic measure for postmenopausal women and men age 50 and older.
The Z-score compares your bone density to others of the same age and sex. A Z-score of -2.0 or lower is described as "below the expected range for age" and may suggest a secondary cause of bone loss. Z-scores are the preferred measure for premenopausal women, men under 50, and children.
WHO Classification Criteria
Normal bone density is defined as a T-score of -1.0 or above. Osteopenia (low bone mass) falls between -1.0 and -2.5. Osteoporosis is diagnosed at -2.5 or below, and severe or established osteoporosis applies when the T-score is -2.5 or below and at least one fragility fracture has occurred.
The lowest T-score across the lumbar spine, total hip, and femoral neck determines the overall diagnosis. In some cases, the 33% radius (forearm) is also measured, particularly when the spine or hip cannot be accurately assessed.
Which Skeletal Site Matters Most?
The femoral neck T-score is used as the input for the FRAX fracture risk assessment tool. The lumbar spine (L1-L4) tends to show changes earlier and is useful for monitoring treatment response. The total hip is considered the best predictor of hip fracture risk. Each site provides different clinical information, so physicians often look at all three together.
How often should I get a DXA scan?
The ISCD recommends baseline DXA screening for all women at age 65 and men at age 70, or earlier if risk factors are present. Follow-up scans are typically done every 1-2 years when monitoring treatment, or every 2-5 years for stable results. Your doctor will determine the right interval based on your individual risk.
Can my T-score improve?
Yes. Medications like bisphosphonates, denosumab, and anabolic agents (teriparatide, romosozumab) can increase bone density and improve T-scores over time. Weight-bearing exercise, adequate calcium and vitamin D intake, and fall prevention also play important roles. Improvements of 3-8% in spine BMD over 2-3 years are common with treatment.
Why is my spine T-score different from my hip?
Different skeletal sites contain different proportions of trabecular and cortical bone. The lumbar spine is rich in trabecular bone, which has a higher turnover rate and responds faster to both bone loss and treatment. The hip contains more cortical bone. It is common for T-scores to differ by 1.0 or more between sites, especially with aging, degenerative changes, or aortic calcification that can falsely elevate spine readings.
What does a low Z-score mean?
A Z-score of -2.0 or lower means your bone density is below the expected range for your age and sex. This may suggest a secondary cause of bone loss such as vitamin D deficiency, hyperparathyroidism, celiac disease, medications (like glucocorticoids), or other metabolic conditions. Further evaluation is recommended to identify and treat the underlying cause.