📋 In This Guide
What a DEXA Scan Measures
DEXA stands for dual-energy X-ray absorptiometry. It's the gold-standard clinical test for measuring bone mineral density (BMD) — how much mineral content (primarily calcium phosphate) is packed into a given area of bone tissue. The "dual-energy" part refers to the two X-ray beams at different energy levels, which allows the machine to distinguish between bone and soft tissue with precision.
The scan measures BMD at specific sites: the lumbar spine (L1–L4 vertebrae) and the hip (typically the femoral neck and total hip). These are the sites most relevant to osteoporotic fracture risk. Some facilities also scan the forearm/wrist, particularly if the hip or spine can't be measured accurately (due to implants, arthritis, or other issues).
What you get is a BMD number — grams of mineral per square centimetre (g/cm²) — plus two derived scores that put it in context: the T-score and the Z-score.
T-Score and Z-Score Explained
T-Score: The Primary Diagnostic Number
The T-score compares your BMD to that of a young adult (typically a 30-year-old of the same sex) at peak bone mass. It's expressed in standard deviations — how many SDs above or below the young adult average your BMD falls.
T-Score Interpretation
WHO diagnostic categories (Kanis et al.). Used for postmenopausal women and men over 50.
- T-score −1.0 or above: Normal bone density
- T-score between −1.0 and −2.5: Osteopenia — bone density below the young adult average, but not yet meeting the diagnostic threshold for osteoporosis. More of a risk state than a disease.
- T-score −2.5 or below: Osteoporosis — the WHO diagnostic threshold. The lower the score, the more bone mass has been lost.
- Severe or established osteoporosis: T-score ≤ −2.5 plus a fragility fracture — this is the most serious category and almost always warrants pharmacological treatment.
One important nuance: T-score tells you density relative to young adult peak. It doesn't directly tell you fracture risk, which also depends on age, fall history, and other factors. A 50-year-old with a T-score of −2.0 and a 75-year-old with the same T-score have very different absolute fracture risks — the 75-year-old is much more likely to fall, and a given fracture is far more consequential. That's why fracture risk assessment tools like FRAX use T-score as one input among many. See our osteoporosis risk factors guide for more on FRAX.
Z-Score: Comparing to Your Age Group
The Z-score compares your BMD to the average for people your age and sex — not to young adult peak. A Z-score of 0 means you're exactly average for your demographic. A Z-score of −2 means your bone density is in the lowest ~2.5% for your age group.
Z-scores are most useful in two situations. First, in younger premenopausal women and men under 50 — using T-scores in these groups can be misleading because some bone density loss with age is normal. In these populations, a Z-score below −2.0 (labelled "below the expected range for age") should trigger investigation for secondary causes of bone loss. Second, in research and clinical monitoring — a very low Z-score flags that something beyond normal aging is driving bone loss, which warrants investigation for underlying conditions like celiac disease, hyperparathyroidism, or medications.
For most Canadians getting their first DEXA in their mid-50s to 70s, the T-score is the clinically actionable number. Ask about your Z-score if you're on the younger end.
Who Should Get Screened in Canada
The 2023 Osteoporosis Canada Clinical Practice Guideline recommends fracture risk assessment for all adults over 50. For most people, this means starting with a clinical assessment (using FRAX or CAROC tools) before ordering a DEXA scan. But there are specific groups for whom a DEXA scan is directly appropriate:
📋 Osteoporosis Canada 2023: Who Should Get a DEXA Scan
- Women 65 and older — routine screening recommended
- Men 70 and older — routine screening recommended
- Postmenopausal women under 65 with clinical risk factors — prior fragility fracture, family history of hip fracture, low body weight, early menopause, smoker, heavy alcohol use, etc.
- Men 50–69 with clinical risk factors — same considerations as above
- Anyone with a prior fragility fracture after age 40 — regardless of age or sex
- Anyone starting systemic corticosteroid therapy for ≥3 months — baseline and monitoring scan appropriate
- Anyone with a disease or medication known to cause bone loss — celiac, IBD, rheumatoid arthritis, aromatase inhibitors, androgen deprivation therapy, long-term anticonvulsants
- Premenopausal women with risk factors or Z-score concern — Z-score interpretation applies here
Editorial opinion: The gap between "routine screening age" (65 for women) and "the age where bone loss becomes significant" (starts in your late 40s for many women, accelerating sharply in the 5 years post-menopause) is a real problem. By 65, some women have already lost 20–30% of peak hip bone mass. If you're in your early 50s, postmenopausal, and have two or more risk factors — family history, smoking, low calcium, physical inactivity — it's entirely reasonable to ask your GP for a DEXA scan now rather than at 65. Many provinces will cover it with clinical justification.
How to Get a DEXA Scan in Canada
The standard path is a referral from your family physician or specialist. Your GP orders the scan based on your age, risk factors, and clinical picture. The referral typically goes to a hospital radiology department or a dedicated bone densitometry clinic. In most provinces, results are sent back to your referring physician.
Some provinces and some private clinics offer direct-access DEXA — meaning you can book without a physician referral — but this typically means paying out of pocket since coverage requires a physician order. Private DEXA scans (for body composition, not medical bone density) are also available at fitness and wellness clinics, but these aren't the same protocol and the results aren't directly comparable to medically-ordered bone density assessments.
If you believe you meet screening criteria but your GP hasn't raised it, bring it up directly. Something like: "I'm 62, postmenopausal, and my mother had a hip fracture. Should I get a bone density test?" is exactly the right conversation to initiate. Most GPs will be receptive; they simply may not have flagged it yet.
Provincial Coverage: OHIP, BC MSP, Alberta, and Others
Coverage for DEXA scans varies significantly by province, and this is an area where information can get outdated — check with your provincial health plan or physician for current details. Here's the general picture as of early 2025:
| Province | Coverage Status | Key Criteria |
|---|---|---|
| Ontario | OHIP covers with referral | Women 65+, men 65+ with risk factors, postmenopausal women under 65 with risk factors, prior fragility fracture, long-term steroid use. Standard repeat interval: 2–3 years. |
| British Columbia | BC MSP covers with referral | BC MSP now funds DXA bone density testing. Requires physician referral and must meet MSP criteria. Repeat interval typically 3 years. Some private clinics offer self-pay if criteria not met. |
| Alberta | Limited / Conditional | Alberta Health Care covers BMD testing for patients meeting clinical criteria. Coverage is not as broad as Ontario or BC. Confirm current criteria with your physician or AHS. |
| Quebec | RAMQ covers with referral | Covered with physician referral for eligible patients. Criteria similar to national guidelines. |
| Manitoba | Manitoba Health covers | Covered with physician referral meeting provincial criteria. |
| Saskatchewan, Nova Scotia, New Brunswick, PEI, Newfoundland | Covered with criteria | Generally covered with physician referral and clinical indication. Specific criteria vary — confirm with your provincial health authority. |
Coverage details reflect general policies as of early 2025. Provincial plans update their criteria. Confirm with your physician or provincial health authority for current eligibility.
Private-pay DEXA is available at various clinics in major Canadian cities for those who want scanning outside the covered criteria. Costs range from roughly $75–200 CAD depending on location and whether a physician interpretation is included. Body composition DEXA (which includes lean mass and fat mass measurements beyond bone density) is typically not covered by any provincial plan.
What to Expect During the Scan
DEXA is one of the simpler medical imaging procedures you'll encounter. Here's what actually happens:
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Preparation: almost none required. No fasting. No contrast dye. No injection. You don't need to change into a hospital gown (though you may need to remove items with metal — belt buckles, underwire bras, zippers near the scan sites). Take your usual medications as normal. If you've had a nuclear medicine scan or barium study in the past week, mention it to the technologist — these can interfere with DEXA. If you take calcium supplements, skip them the morning of the scan (excess calcium in the GI tract can slightly skew readings).
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Radiation exposure is minimal. A DEXA scan delivers roughly 1–10 microsieverts of radiation — comparable to a few hours of background radiation from the environment, and dramatically less than a chest X-ray (approximately 100 microsieverts) or CT scan. Pregnancy is the only common contraindication; mention it to the technologist if there's any possibility.
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You lie on a padded table. For the hip scan, a foam block positions your leg at a specific angle (this helps reproducibility between scans). For the spine scan, your knees are raised with a support. You don't need to hold still in the way you would for a CT scan — breathing normally is fine.
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The scan arm passes over you. The machine arm moves slowly along your body, taking two-dimensional X-ray images. The hip and femoral neck scan takes 2–3 minutes; the spine takes 2–3 minutes. Total scan time including positioning is typically 15–20 minutes from when you walk in to when you're done.
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You can watch the images appear. In most facilities, you can see the scan on the technologist's screen as it proceeds. The raw images look like outlines of your spine or hip — bone appears white against the grey background. The software calculates BMD from the image automatically.
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Results go to your referring physician. The radiologist writes a formal report; your GP receives it. You may get a copy directly depending on the facility and province. In Ontario, you can request your report through services like PocketHealth. Expect your physician follow-up within 1–2 weeks of the scan.
How Often to Repeat a DEXA Scan
The answer depends on your results and circumstances — there's no single universal answer. General guidance from the 2023 Osteoporosis Canada guidelines:
- Normal bone density (T-score above −1.0), no significant risk factors: Routine re-testing is generally not required for 5–10 years. Bone density changes slowly in low-risk individuals.
- Osteopenia (T-score −1.0 to −2.5): Re-test every 2–3 years is typical clinical practice to monitor trajectory. If stable, intervals can be extended.
- Osteoporosis (T-score −2.5 or below): If starting pharmacological treatment, a follow-up scan 2 years after initiating therapy is standard to assess treatment response. Ongoing monitoring as directed by your physician.
- On corticosteroids: Annual monitoring is often warranted during active steroid therapy, given the rate of bone loss.
- Significant new risk factors: A new fragility fracture, starting a bone-toxic medication, or a major change in health status all justify repeat scanning regardless of when the last one was done.
One practical point: if you're being followed over time, try to get repeat scans done on the same model of DEXA machine at the same facility when possible. Different machine manufacturers have slightly different calibrations, and comparing a result from a Hologic machine to a GE machine introduces noise into longitudinal monitoring. Your radiologist or physician should note which machine was used on each report.
What to Do With Your Results
A DEXA result is a starting point for a conversation, not an endpoint. Here's how to think about the most common scenarios:
Normal T-Score (≥ −1.0): No Action Beyond Prevention
Good news, but not a green light to stop caring about bone health. Continue or start resistance training, ensure adequate calcium and vitamin D, avoid smoking. Routine re-scanning as per guideline intervals. Nothing urgent to do, but this is the time when prevention is easiest and most effective.
Osteopenia (−1.0 to −2.5): Active Prevention and Monitoring
Osteopenia doesn't mean fractures are imminent. It means you're below the young adult average and should be actively protecting your bone density. The key questions with your GP: What's driving this? What are my other risk factors? What's my FRAX or CAROC fracture risk estimate? For many people in this range, lifestyle measures — serious resistance training, optimizing calcium and vitamin D, stopping smoking — are the primary intervention. Pharmacological treatment is considered for those in the osteopenia range with high fracture risk scores (prior fracture, high FRAX).
Osteoporosis (≤ −2.5): Active Management Required
A T-score below −2.5 warrants a full conversation with your physician about pharmacological treatment, not just lifestyle measures. First-line treatment in Canada is bisphosphonate therapy (alendronate/Fosamax, risedronate/Actonel, or zoledronic acid/Reclast) — these reduce fracture risk by 30–50% for vertebral fractures and 20–40% for hip fractures. Calcium and vitamin D should be optimized as adjuncts to medication, not replacements for it. A follow-up DEXA in 2 years to assess response is standard.
Also: fall prevention becomes critical. Home safety assessment (removing trip hazards, bathroom grab bars), balance training, appropriate footwear — these practical interventions matter as much as the T-score number.
Prior Fragility Fracture + Any T-Score: Treat as High Risk
A fragility fracture changes the picture regardless of T-score. The fracture itself is the clinical event that tells you the bones aren't coping. Canadian guidelines recommend pharmacological treatment after a fragility fracture even in the osteopenia range. This is an area where many Canadians are undertreated — fracture liaison services (coordinated care after fracture) exist in some major Canadian centres specifically to close this gap.
Questions to Ask Your Physician
- What are my T-scores at the hip and spine separately? (They can differ significantly)
- What is my FRAX or CAROC fracture risk estimate with these numbers?
- Are there secondary causes worth investigating given my results?
- Should I start, adjust, or continue bone medication?
- When should I repeat this scan?
- What calcium and vitamin D should I be taking, given my results and diet?