DEXA Scan (Bone Density)
Bone · Imaging
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About this test
What is a DEXA Scan?
A DEXA (Dual‑Energy X‑ray Absorptiometry) scan is a quick, painless imaging test that measures bone mineral density (BMD) and helps assess bone strength.
Key Parameters
| Parameter | What it shows |
|---|---|
| T‑score | Standard deviation from the average bone density of a healthy young adult. |
| Z‑score | Standard deviation from the average bone density of people of the same age, sex, and ethnicity. |
| Bone Mineral Density (g/cm²) | Absolute measurement of bone mineral content per unit area. |
Why It Is Done
- Routine screening for osteoporosis in post‑menopausal women and men >50 years.
- Evaluation of bone loss after conditions like prolonged steroid use, rheumatoid arthritis, or chronic kidney disease.
- Monitoring response to osteoporosis treatment (e.g., bisphosphonates, denosumab).
- Assessing fracture risk in patients with a history of low‑impact fractures.
Early Detection
A DEXA scan can help identify early signs of osteoporosis or osteopenia, but it does not diagnose a disease on its own. A clinician interprets the result alongside symptoms, history, and other investigations.
What Abnormal Results May Indicate
- Low BMD (T‑score ≤‑2.5) suggests osteoporosis, increasing fracture risk.
- Moderate loss (T‑score between ‑1.0 and ‑2.5) indicates osteopenia, a precursor to osteoporosis.
- High BMD is uncommon but may be seen in conditions like osteopetrosis or certain endocrine disorders.
Factors such as hydration status, recent calcium intake, medications (e.g., steroids, anticonvulsants), and body composition can influence results.
Who Might Be Advised to Get a DEXA Scan
- Post‑menopausal women and men >50 years.
- Individuals with risk factors: family history of osteoporosis, long‑term steroid use, low body weight, smoking, excessive alcohol use, or chronic diseases affecting bone metabolism.
- Patients who have sustained a low‑impact fracture.
Quick Takeaway
A DEXA scan is a safe, non‑invasive way to measure bone density and gauge fracture risk, helping guide prevention and treatment strategies.
Used for detecting / monitoring
Before your test
Preparation for a DEXA Scan
- Fasting: Not required.
- Other tests: If you are also having a fasting blood test, follow the fasting instructions for that test.
- Procedure: You will lie on a padded table while a small, low‑dose X‑ray machine scans your hip and spine. The scan takes about 10–20 minutes.
- Discomfort: None; the procedure is painless.
- Precautions: Remove any metal objects (jewelry, piercings) that could interfere with the scan. Inform the technician if you have a pacemaker or other implanted device.
- After the scan: You can resume normal activities immediately.
- Note: Confirm any specific preparation details with your doctor or the lab. This information is educational and not a substitute for professional medical advice.
Sample type: Imaging
Report parameter guide
T-score
A numerical value that compares your bone density to that of a healthy young adult of the same sex, indicating how much bone strength you have relative to a reference population.
Low: A low T-score (generally below -1) can indicate reduced bone density, which may be related to conditions such as osteopenia, early osteoporosis, or risk factors like aging, hormonal changes, or low calcium intake.
High: A high T-score (generally above -1) indicates bone density that is normal or higher than average, suggesting a lower risk of fractures and generally healthy bone strength.