Bone is a living tissue. It is constantly being broken down and rebuilt, and from about age 30 onward, the breakdown gradually outpaces the rebuilding for most people. You feel none of this. The first sign of significant bone loss for many people is a fracture from a fall that should not have caused one.
A DEXA scan is the standard way to measure bone density before that fracture happens — and to identify the people who need treatment.
Why screen for low bone density at all?
Osteoporosis affects more people than most realise:
- About 1 in 3 women and 1 in 5 men over age 50 will have an osteoporotic fracture in their lifetime.
- Hip fractures in older adults carry a significant risk of long-term disability and reduced life expectancy.
- Effective treatments exist that meaningfully reduce fracture risk — but they only help if low bone density is identified first.
DEXA is the test that connects "you have invisible bone loss" to "we should do something about it."
Who should consider a DEXA scan?
Nigeria does not have one universally adopted population DXA screening schedule. International guidance differs, so the recommendations below separate evidence-backed population screening from individual clinical indications.
Age-based screening
- The 2025 USPSTF recommends screening women aged 65 and over.
- It also recommends risk assessment first for postmenopausal women under 65 with one or more risk factors, followed by DXA when increased risk is identified.
- For men, the USPSTF found the evidence insufficient for population screening. Other specialist organisations use age- or risk-based thresholds, so men should make an individual decision with a clinician.
Earlier screening for higher-risk adults
A DEXA scan is also recommended at a younger age if any of the following apply:
- Postmenopausal women under 65 with one or more risk factors (see below).
- Men aged 50 to 69 with one or more risk factors.
- Anyone with a low-trauma (fragility) fracture after age 50 — for example, a hip, wrist, or vertebral fracture from a fall from standing height.
- Anyone on long-term oral steroids (prednisolone equivalent of 5 mg/day or more for 3 months or longer).
- Anyone with a medical condition known to weaken bones, such as rheumatoid arthritis, inflammatory bowel disease, coeliac disease, hyperthyroidism, hyperparathyroidism, chronic kidney disease, or early menopause.
Premenopausal women and younger men
DEXA is not used for routine screening in this group, but it is appropriate if there is:
- A fragility fracture.
- A medical condition or medication that affects bone.
- A suspected eating disorder or significantly low body weight.
- Unexplained loss of height or back pain that raises the question of vertebral fracture.
Major risk factors that lower the screening threshold
If any of these apply to you, talk to your doctor about a DEXA scan earlier than the standard age cutoff:
- Family history of osteoporosis or hip fracture, especially in a parent.
- Personal history of fracture from a fall from standing height after age 50.
- Low body weight (BMI under 19) or recent unexplained weight loss.
- Smoking, current or long-term past.
- Heavy alcohol use (more than 2 to 3 units a day).
- Long-term steroid use.
- Early menopause (before age 45) or surgical menopause without hormone replacement.
- Conditions affecting nutrient absorption (coeliac, inflammatory bowel disease, after bariatric surgery).
- Hormone-affecting cancer treatments such as aromatase inhibitors for breast cancer or androgen-deprivation therapy for prostate cancer.
What about younger people who exercise a lot?
Very high training loads paired with low energy availability — common in long-distance runners and some dancers, of any sex — can cause low bone density at surprisingly young ages. If you have had stress fractures, irregular periods (in women), or unexplained bone pain, a DEXA scan may be appropriate even in your 20s or 30s.
I have no risk factors and I am under 65. Do I really need this?
If you genuinely have none of the risk factors above and are under the age cutoffs, routine DEXA is generally not needed. Spending the money instead on weight-bearing exercise, adequate protein, calcium and vitamin D in your diet, and not smoking is more impactful at this stage. A DEXA scan becomes more useful as you approach menopause or age 65.
How do I get a DEXA referral?
In Nigeria, most DEXA scans are arranged through your doctor — a GP, gynaecologist, endocrinologist, or orthopaedic surgeon. Walk-in or self-paid DEXA is offered by some private imaging centres for patients who want to know their numbers without a referral. The report will go to your doctor for interpretation.
What happens after a positive screen?
A low T-score is not a sentence
Finding osteopenia or osteoporosis on a DEXA scan is good news in the sense that it is information you can act on. There are effective treatments and lifestyle interventions that meaningfully reduce fracture risk. The patients who do badly are usually the ones who never knew their bones were weak until a fracture happened.
If your scan shows osteopenia or osteoporosis, your doctor will combine the result with your overall fracture-risk profile (often using a FRAX score) to decide:
- Whether lifestyle measures alone are enough.
- Whether to start calcium and vitamin D.
- Whether to start an osteoporosis-specific medication.
- How often to repeat the DEXA to monitor response.
What are the important limitations?
DXA measures two-dimensional areal bone mineral density; it does not measure every aspect of bone strength. Arthritis, vertebral compression, calcification, previous surgery, metalwork, positioning, and differences between machines can distort results. Fracture risk must combine the usable DXA sites with age, previous fractures, medicines, falls, medical conditions, and—when appropriate—a validated risk tool.
A fragility fracture can justify an osteoporosis diagnosis or treatment assessment even when the T-score is not in the osteoporosis range. For monitoring, compare valid studies from the same facility and machine where possible, and only call a change real when it exceeds that facility's least significant change (LSC). The timing of another scan should be individualised.
Questions to ask your care team
- Which sites were usable, and did arthritis, fracture, surgery, or metal affect the measurement?
- Should my report be interpreted using T-scores, Z-scores, fracture history, or a risk calculator?
- If this is a repeat study, was it compared with the correct baseline and did the change exceed the facility's LSC?
- Does the result change treatment now, and what clinical reason determines the timing of any repeat DXA?
Sources and further reading
- International Society for Clinical Densitometry: 2023 Adult Official Positions
- RadiologyInfo.org: Bone density scan (DXA)
- USPSTF: Osteoporosis screening, 2025
Conclusion
DXA is recommended for women aged 65 and over and for younger postmenopausal women found to be at increased risk. Men and people with fractures, bone-affecting conditions, or relevant medicines need an individual clinical assessment rather than a one-size-fits-all age rule. The scan is valuable only when its result will inform prevention or treatment.