Why Doesn’t My BodySpec DEXA Scan Show a T-Score or Z-Score?

6 MIN READ • BY The BodySpec Team • Aug 20, 2026

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Why Doesn't My BodySpec DEXA Scan Show a T-Score or Z-Score?

The content on this page is for general informational and educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before making changes to your health or fitness regimen.

Have you ever been eager to see your bone-density scores after a DEXA scan, only to find they're missing from your report?

T-scores and Z-scores come from site-specific diagnostic DEXA exams of the spine, hip, or forearm (Johns Hopkins Medicine, 2023). In BodySpec's whole-body composition scan, the T-score is left off because the protocol is non-diagnostic. The Z-score is missing for a different reason: the legacy manufacturer reference was built on a different scanner make and positioning protocol than BodySpec uses, so it isn't an appropriate comparison for our scans—and BodySpec's own reference hasn't been released yet.

Understanding how different scan protocols and reference standards shape which metrics appear can help you choose the DEXA exam that fits your health and fitness goals.

What Are T-Scores and Z-Scores?

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A T-score compares your bone mineral density (BMD) to that of healthy young adults of the same sex, while a Z-score compares it to individuals of the same age, sex, and ethnicity (MedlinePlus, 2024). The World Health Organization uses T-score thresholds to classify osteoporosis and osteopenia (International Osteoporosis Foundation, 2024). Dual-energy X-ray absorptiometry (DEXA) is widely accepted as the gold standard for measuring BMD, with guidelines emphasizing its precision and reproducibility (ISCD, 2026). Updated practice guidelines also highlight the need for standardized scanning and analysis protocols to ensure accuracy across facilities (ISCD, 2026).

Reasons Your T-Score or Z-Score Might Be Missing

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Whole-Body Protocols Are Non-Diagnostic (No T-Score): BodySpec's full-body composition scans measure bone density but are non-diagnostic; they do not provide a clinical T-score. T-scores typically come from site-specific diagnostic DEXA exams of the spine, hip, or forearm (Johns Hopkins Medicine, 2023). Learn more about these differences in our article DEXA body composition vs bone density: Which scan is right for you.
Historic NHANES Reference: A patient's bone-density and body-composition values can differ substantially between DXA systems from different manufacturers, because of differences in calibration, hardware, and software algorithms (Journal of Clinical Densitometry, 2007). The manufacturer's legacy Z-score drew on the NHANES dataset, which was collected on Hologic densitometers. BodySpec scans on GE machines, and our technicians use Nana positioning rather than the NHANES protocol—so we rely on our own reference rather than the manufacturer's NHANES-derived comparison.
BodySpec's Reference Database: BodySpec relies on a proprietary dataset of over 700,000 whole-body scans collected on GE machines with the hands positioned palms-in, facing the thighs (Nana positioning). This gives our reference greater statistical power than NHANES, which uses only a few thousand participants per two-year cycle. Rather than a raw Z-score, BodySpec currently reports how you compare against this database primarily as percentiles. Nana positioning is a widely accepted, standard clinical protocol that BodySpec technicians are trained and licensed on. Because the palms-in orientation captures a bit less hand surface area, it lowers the denominator in the areal bone-density calculation and tends to yield slightly higher bone-density values than the palms-flat NHANES positioning, which isn't a standard clinical protocol. BodySpec's lead clinical advisor and the doctors we work with agree that this tailored reference yields more accurate bone-density comparisons.

It's a bit like shoe sizes. If you measure your foot as a size 9 in one brand, then judge that number against a different brand's sizing—where a 9 fits differently—the comparison misleads you, even though your foot hasn't changed. Your bone-density measurement works the same way: comparing a BodySpec scan against a reference population built on a different machine and different positioning isn't an appropriate comparison, even when both measurements are accurate on their own.

An abstract illustration depicting a large, multi-colored group of person icons surrounding a central gold cylindrical database icon. Light blue lines connect the database to many of the person icons, symbolizing data flow or connections.

Comparative Table: Scan Types and Score Reporting

Scan Type	T-Score	Z-Score
Whole-Body Composition Scan (BodySpec)	No	Not yet
Site-Specific Diagnostic DEXA (spine, hip, forearm)	Yes	Yes

Keep in mind that a whole-body scan does measure your bone density. The missing T-score simply reflects the scan's non-diagnostic nature, and the missing Z-score reflects a change in the reference population used for comparison—not an absence of bone measurement.

Want to see how your bone density compares? Use BodySpec's digital report builder in your dashboard to compare your past and current results against BodySpec's own reference database. Because that database is built on the same GE machines and the same positioning as your scan, it gives you an apples-to-apples comparison—a more useful benchmark than the old manufacturer reference. Your doctor can review these results too.

Does Changing the Reference Group Affect Your Results?

The raw bone-density measurement from your scan hasn't changed—only the population it's compared against has. Since a Z-score or percentile just reflects how you compare to a chosen reference group, switching that group can shift the score even though the underlying measurement stays the same. Your previous results are still valid, and there's no cause for concern.

What's Coming

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Today, BodySpec expresses your results against its own database primarily as percentiles. BodySpec also plans to introduce a Z-score based on this reference population, matched to our GE-machine, palms-in methodology. When released, this Z-score will differ from the legacy NHANES-derived manufacturer Z-score. Make sure you're ready by reviewing how to prepare for your BodySpec scan.

Can I Request a Diagnostic Scan Through BodySpec?

Physician-ordered diagnostic DEXA exams for the spine, hip, or forearm are performed at medical imaging centers; these site-specific tests deliver T-scores and Z-scores. BodySpec does not currently offer these, but may do so in the future.

Conclusion

Knowing why your DEXA scan doesn't show a T-score or Z-score makes it easier to choose the right protocol for your goals—whether that's diagnostic bone-density testing or full-body composition analysis. For comprehensive insights into your body composition, book your next BodySpec DEXA scan and uncover the metrics that matter.