Osteoporosis screening criteria and interpreting DEXA scan results

I didn’t plan to spend my evening decoding a bone-density report, but there I was, staring at a string of numbers, arrows, and abbreviations that felt oddly personal. It struck me that bones carry a quiet biography—years of movement, pauses, hormones, meals, stress, sunlight. I wanted to capture what helped me make sense of screening criteria and those infamous DEXA (technically “DXA”) scores, in plain language, without hype or panic.

The moment a DEXA report stopped looking like alphabet soup

My turning point was realizing that a DEXA printout is more map than verdict: it shows where I am today and hints at how things might change, but it doesn’t tell my future. One early, high-value takeaway for me: the T-score guides diagnosis in postmenopausal women and men age 50+, while the Z-score (age-matched) is what matters for premenopausal women and men under 50. Another: diagnosis isn’t limited to a single spot; hip and spine are both central, and the forearm (33% radius) can matter in certain cases. Understanding these basics instantly made the report less intimidating.

• T-score thresholds: normal (≥ −1.0), low bone mass/osteopenia (−1.0 to > −2.5), osteoporosis (≤ −2.5).
• Sites that count: lumbar spine (PA L1–L4), total hip, femoral neck; forearm (33% radius) in select scenarios.
• Context matters: arthritis and calcifications can artificially elevate spine BMD; technicians often exclude abnormal vertebrae and use the rest.

For orientation, I bookmarked a few concise primers I found trustworthy and revisit them when I’m unsure:

• USPSTF Osteoporosis Screening (2025)
• ISCD 2023 Adult Official Positions
• BHOF Bone Density Testing
• FRAXplus Fracture Risk Tool

Who actually needs a bone density test

Screening exists to prevent fractures, not to label anyone. The latest U.S. Preventive Services Task Force (USPSTF) recommendation (January 14, 2025) lands here: screen all women 65+; also screen postmenopausal women younger than 65 if a formal risk assessment suggests higher risk. For men, the USPSTF says evidence is insufficient to recommend for or against routine screening, which doesn’t mean “never”—it means decisions should be individualized based on risk and professional guidance.

Other specialty groups offer pragmatic cues. The Bone Health & Osteoporosis Foundation (BHOF) and the Endocrine Society commonly support testing in men 70+ and in men 50–69 with risk factors such as prior adult fracture, low body weight, glucocorticoid use, or smoking. In practice, many clinicians blend the population-level USPSTF stance with these condition-specific guidelines.

• Screen now: Women ≥65; postmenopausal women <65 with elevated risk (formal tool, e.g., FRAX-based or equivalent); men with clear risk per specialty guidance.
• Consider sooner: Anyone ≥50 with a low-trauma (fragility) fracture; people starting or on long-term steroids; those with disorders or medications that accelerate bone loss.
• Personal factors: Early menopause, parental hip fracture, low BMI, smoking, heavy alcohol use, rheumatoid arthritis, and certain endocrine or GI conditions.

On frequency, cohort data summarized by USPSTF suggest that repeating BMD every 4–8 years doesn’t necessarily improve fracture prediction for average-risk people with stable results. On the other hand, monitoring after therapy initiation or in higher-risk situations is often done sooner (about 1–2 years) to confirm direction of change. The thread running through all of this: match the interval to risk and to what the result would change in your plan.

How I read a DEXA report without panicking

This is the routine I now follow when I receive a printout. It keeps me grounded and helps me have a focused conversation with my clinician:

• Step 1 — Identify the sites and numbers: I look for BMD in g/cm² and the T-scores at the lumbar spine (PA L1–L4), total hip, and femoral neck. If there’s a forearm site (33% radius), I note it too. Diagnosis in postmenopausal women and men 50+ is based on the lowest T-score among the valid central sites; the 33% radius can be used in certain circumstances (e.g., hyperparathyroidism or when hip/spine are uninterpretable).
• Step 2 — Watch for exclusions and artifacts: Reports may exclude vertebrae that are structurally abnormal or outliers. That’s not a mistake; it’s a quality safeguard to avoid false reassurance from degenerative changes.
• Step 3 — Separate diagnosis from risk: A T-score ≤ −2.5 supports densitometric osteoporosis, but fracture risk involves more than one number. Age, prior fractures, medications, and FRAX probabilities shape the bigger picture.
• Step 4 — Mind the Z-score when it applies: If you’re premenopausal or a man <50, the Z-score tells whether bone density is “within” or “below” the expected range for age. A Z ≤ −2.0 (“below expected”) may prompt a search for secondary causes.
• Step 5 — Ask for the facility’s LSC: The least significant change (LSC) is the smallest change considered real (not measurement noise). It’s based on the scanner’s precision; many centers calculate it with a 95% confidence method. If my follow-up change doesn’t exceed the LSC, I treat it as “no significant change.”

Two optional extras sometimes included:

• TBS (Trabecular Bone Score): A texture-based metric derived from the lumbar spine image; it can refine fracture risk estimation and adjust FRAX probabilities in some reports.
• VFA (Vertebral Fracture Assessment): A low-dose lateral spine image to spot silent vertebral fractures that dramatically shift risk and management.

When FRAX changes the picture even with borderline scores

When the T-score lives in the “low bone mass” range (−1.0 to > −2.5), I’ve learned to pay special attention to FRAX, the 10-year fracture probability tool. In the U.S., a common treatment threshold for people with osteopenia is a hip fracture risk ≥ 3% or a major osteoporotic fracture risk ≥ 20%. That’s not a rule for every person, but it’s a well-used starting point for discussions about medication alongside lifestyle work. FRAX can be run with or without a femoral-neck BMD value; adding BMD usually sharpens the estimate.

• Why FRAX matters: Two people can share the same T-score but have very different risks due to age, prior fractures, steroids, smoking, or rheumatoid arthritis.
• Use it thoughtfully: FRAX is calibrated by country, is most accurate for untreated adults 40–90, and may underestimate risk after certain fractures (e.g., vertebral) unless those are entered correctly.
• Bring the printout: If your DEXA report includes FRAX, circle both the hip and major osteoporotic probabilities. If it doesn’t, you and your clinician can calculate it together.

How often to repeat a scan without overtesting

I used to assume “more often is better,” but that’s not how measurement works. Bone density changes slowly, and scanning too soon can blur signal with noise. Broadly speaking, if you’re average-risk with stable results, evidence summarized by USPSTF indicates that repeating within 4–8 years may not improve prediction. If you’ve just started medication, many clinicians recheck within 1–2 years to see if the trend is stabilizing or improving and to confirm adherence and response. After that, intervals often stretch depending on risk, age, and prior results.

• Ask what a new test would change: The best interval is the one that could alter your plan.
• Mind precision: Always compare the same site (e.g., total hip to total hip), same machine if possible, and check whether the change exceeds the facility’s LSC.
• Don’t delay care for a scan: If you’ve had a fragility fracture, management decisions shouldn’t wait for a perfect number.

Little habits I’m testing while watching the numbers

None of this replaces professional advice, but here are routines I’ve been trying to stack—because a steady cadence beats heroic sprints that fade:

• Protein with purpose: I build meals around a source of protein plus calcium-rich foods (dairy, fortified alternatives, leafy greens) and keep an eye on overall intake.
• Weight-bearing + resistance: Short daily walks, stair time, and two resistance sessions weekly (even bodyweight) feel doable. Balance drills sneak in while my coffee brews.
• Medication audit: I keep a list of meds and supplements to review with my clinician, especially if any might affect bone (e.g., steroids, certain endocrine or GI meds).
• Sunlight and vitamin D: I don’t assume; I verify with labs if needed and adjust only with guidance.
• Fall-proofing: Night lights, clear walkways, grippy shoes—unromantic but powerful.

When nudging habits, I like anchoring to reputable playbooks. These two have been especially practical for step-by-step use:

• BHOF Bone Density Testing
• USPSTF Screening Summary

Signals that tell me to slow down and double-check

I keep a short list of “pay attention” moments. Clear language helps me act without catastrophizing:

• A new low-trauma fracture (e.g., a wrist from a standing-height fall) — that’s a red flag to seek care promptly and re-evaluate prevention or treatment.
• Unexpected height loss, new or worsening back pain, or posture change — can hint at vertebral fractures; VFA or X-ray may be discussed.
• A big swing in BMD that doesn’t exceed the LSC — might be noise; I ask whether positioning or machine differences could explain it.
• Z-score ≤ −2.0 in a younger person — I’d ask about labs for secondary causes (thyroid, parathyroid, celiac, kidney, meds).
• Borderline T-scores with high FRAX — a cue to talk through the pros/cons of medications, falls prevention, and follow-up timing.

My plain-English checklist for the next DEXA

• Confirm the sites scanned (PA L1–L4 spine, total hip, femoral neck; forearm if needed).
• Write down BMD (g/cm²), T-score or Z-score (as appropriate), and FRAX probabilities.
• Ask for the facility’s LSC and whether the change from prior exceeds it.
• Note any vertebrae excluded and why; save the report for consistent comparisons.
• Decide on a realistic rescan interval tied to what the result would change.

What I’m keeping and what I’m letting go

I’m keeping the mindset that bone health is a long game. Two or three principled ideas help me stay on track:

• Seek signal over noise: Compare like-with-like, respect the LSC, and avoid overreacting to small wiggles.
• Treat the person, not just the number: Prior fracture history, FRAX, symptoms, and preferences matter as much as T-scores.
• Consistency beats intensity: Sustainable nutrition, movement, and fall-proofing carry more weight than occasional bursts.

When in doubt, I revisit the same core sources (USPSTF for who/when to screen, ISCD for how to measure and interpret, BHOF for patient-friendly guidance, and FRAX for probabilistic risk). They don’t agree on every nuance, but together they make a sturdy compass.

FAQ

1) Do I need a DEXA if I feel fine and have no risk factors?
Answer: If you are a woman 65 or older, major guidelines recommend screening even without symptoms. If you’re younger and postmenopausal, or a man, your situation depends on risk factors and shared decision-making with a clinician.

2) My T-score is −2.3. Is that osteoporosis?
Answer: Not by densitometric criteria; −2.3 is in the “low bone mass/osteopenia” range. But your overall fracture risk could still be high depending on age, past fractures, steroids, and FRAX—those pieces guide next steps.

3) The report shows improvement but the doctor says it’s “not significant.” Why?
Answer: Changes must exceed the facility’s least significant change (LSC) to be considered real. If the gain doesn’t clear that threshold, it may reflect measurement variability rather than true change.

4) How often should I repeat a DEXA?
Answer: It depends. After starting medication, many clinicians repeat at about 1–2 years to check the trend. Otherwise, longer intervals are common; repeating within 4–8 years hasn’t clearly improved prediction for average-risk people with stable results. Your plan should reflect your risk and what the result would change.

5) What’s the difference between T-score and Z-score again?
Answer: T-score compares you to healthy young adults and is used for diagnosis in postmenopausal women and men 50+. Z-score compares you to people your own age and is used to judge whether bone density is typical or unexpectedly low in premenopausal women and men under 50.

Sources & References

• USPSTF Osteoporosis Screening (2025)
• ISCD Adult Official Positions (2023)
• BHOF Bone Density Testing (2022)
• FRAXplus Fracture Risk Tool
• JAMA USPSTF Recommendation Statement (2025)

This blog is a personal journal and for general information only. It is not a substitute for professional medical advice, diagnosis, or treatment, and it does not create a doctor–patient relationship. Always seek the advice of a licensed clinician for questions about your health. If you may be experiencing an emergency, call your local emergency number immediately (e.g., 911 [US], 119).