How to read your bone density results
A T-score on its own tells you very little. Here's what each number on your report actually measures, what the thresholds mean, and what should happen next — with a real REMS report, annotated.
Texas Bone Health Specialists Editiorial
What's actually on the report
Most people leave a bone density scan holding a page of numbers and a word — normal, osteopenia, or osteoporosis — and very little sense of what to do about it. The numbers aren't complicated once you know what each one is comparing you to.
A REMS report runs to five pages. Page one carries the headline numbers — bone mineral density, T-score, Z-score, and a diagnosis — plus a fracture risk box. Page two breaks out the fragility score. Page three is where density and bone quality are combined into a risk class, and it's the page most people never have explained to them. Page four covers body composition. Page five shows the raw ultrasound images, marked "not for diagnostic purposes," which are there so the technologist can verify the scan was captured properly.
Each number answers a different question, so it's worth taking them one at a time.
T-score: how you compare to a healthy young adult
Your T-score compares your bone density against the average for a healthy 30-year-old of your sex — roughly peak bone mass. It's expressed as the number of standard deviations above or below that average, which is why it's usually a negative number and why that's not automatically alarming.
Your density is plotted against the expected range for your age. The green, yellow and red bands are the three T-score classifications, and the marker is you. Simplified here for clarity — on your report the bands are plotted against reference data for your age and sex.
The same information as numbers. In this sample: a T-score of −0.5 and a Z-score of −0.4, classified normal. BMD is the raw measurement; the two scores express it as standard deviations from two different reference groups.
These thresholds come from the World Health Organization and are the standard used internationally. They're a classification, not a diagnosis — a T-score of −2.6 doesn't mean you'll fracture, and −1.2 doesn't mean you're safe.
Z-score: how you compare to people your own age
The Z-score makes the same comparison against people of your age, sex and body size. It answers a different question: is this normal for someone like me, or is something else going on?
A Z-score at or below −2.0 is generally described as below the expected range for age, and usually prompts a look for a secondary cause — a medication, an absorption problem, a hormonal or thyroid issue — rather than treating it as ordinary age-related loss.
For anyone premenopausal, or men under 50, the Z-score is typically the more relevant of the two.
So why is the T-score the one used for diagnosis?
Because fracture risk tracks absolute bone density, not how you compare to your peers. Bone loss is normal with age, so a Z-score grades you on a curve — if everyone your age has lost bone, an average Z-score can look reassuring while your actual density sits well into the range where fractures happen.
The T-score measures against peak bone mass instead, which is a fixed reference. That makes it the number that corresponds to risk, and it is why the World Health Organization built the osteopenia and osteoporosis thresholds around it (WHO technical report, 1994).
The Z-score still earns its place — it answers a different question. Not "how much bone have I lost," but "is this more than I'd expect at my age, and is something else causing it?"
Fragility score: why density isn't the whole story
Density tells you how much mineral is in the bone. It doesn't tell you how well that bone is structured — and two people with identical density can have quite different bone strength.
The fragility score is a REMS-specific measure of bone structure, and the report states plainly that it is independent of BMD. It runs from 0 to 100, and unlike the T-score, higher is worse.
It's plotted against age, with three bands: normal, decreased, and low. The bands shift with age, so the same score means something different at 40 than at 70. In the sample report, a score of 19.8 at age 33 sits in the normal band.
One naming quirk worth knowing, because it trips people up: the band labelled "low" is the worst of the three. It refers to low bone quality, not a low score.
The fragility score plotted against age. Higher is worse, and the bands rise with age — the same score is read differently at 70 than at 30. This sample scores 19.8 at age 33, comfortably in the normal band.
In a five-year study of 1,989 patients, the fragility score predicted fractures better than T-scores did, in both women and men (Pisani et al., 2023).
Five-year fracture risk
This is the number that matters day to day, and it's the one the report builds last — because it combines the other two.
How density and quality are combined
Page three of the report has a grid. Your T-score classification runs across the top — normal, osteopenia, osteoporosis. Your fragility score classification runs down the side — normal, decreased, low. Where they meet gives you a risk class from R1 to R7.
That grid is the most useful thing in the whole report, because it shows why two people with the same T-score can end up in different places. Normal density with low bone quality lands at R3 — the same risk class as osteopenia with normal quality. Density alone would have told you those two people were fine and not fine respectively. The combination says otherwise.
What the risk classes mean
Each class corresponds to a rate of major osteoporotic fracture, expressed per 1,000 people over five years.
How it appears on page one: the fragility score out of 100, and the five-year risk. This sample reads ≤ 5‰ — five or fewer people per thousand over five years, not five per cent.
These are population rates for people whose scans look like yours, not a prediction about you. Their value is as a starting point for a decision: whether to change something, and how urgently.
Seeing the whole thing
Everything above is rebuilt from a five-page sample report. The two pages not covered here are body composition — BMI, body fat against age-banded ranges, and estimated metabolism — and the raw ultrasound captures for each vertebra, which are marked "not for diagnostic purposes" and exist so the technologist can confirm the scan was taken properly.
What your results should prompt
No single result dictates one course of action, but broadly:
If you're in the normal range, the useful thing is a baseline. You now have a number to measure against, and the next scan is what tells you whether anything is changing.
If you're in the osteopenia range, this is the point where changes have the most leverage — nutrition, loading and strength work, and addressing anything that's driving loss. It's also the point at which rescanning matters most, because you want to know whether what you're doing is working.
If you're in the osteoporosis range, this is a conversation with your physician as well as with us. There are medications that meaningfully reduce fracture risk, and the decision about whether they're right for you is a clinical one.
Why REMS and DXA numbers aren't interchangeable
If you have had a DXA scan before, do not put the two T-scores side by side and read the difference as progress or decline. The two technologies measure bone differently. They agree closely at a population level — a multicentre study of 1,914 postmenopausal women found significant agreement between the two (Di Paola et al., 2019) — but an individual's scores are not directly interchangeable.
That doesn't make either one wrong. It means you should track change within one technology, and bring your previous reports so whoever reads your scan can interpret it with the full picture. More on how REMS and DXA compare.
What to ask
Whoever reviews your results, these are worth asking:
Which number are we tracking, and what would a meaningful change look like? Is there anything in my history or medication list that could be driving this? What's the single thing most likely to help? And when should I be measured again?
References
Pisani P, et al. Fragility Score: a REMS-based indicator for the prediction of incident fragility fractures at 5 years. Aging Clinical and Experimental Research, 2023. PubMed
Adami G, et al. Radiofrequency echographic multi spectrometry for the prediction of incident fragility fractures: a 5-year follow-up study. Bone, 2020. PubMed
Di Paola M, et al. Radiofrequency echographic multispectrometry compared with dual X-ray absorptiometry for osteoporosis diagnosis. Osteoporosis International, 2019. PubMed
World Health Organization. Assessment of fracture risk and its application to screening for postmenopausal osteoporosis. WHO Technical Report Series 843, 1994. WHO
Icătoiu E, et al. Radiofrequency echographic multi spectrometry: a novel tool in the diagnosis of osteoporosis and prediction of fragility fractures — a systematic review. Diagnostics, 2025. PubMed
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