Bones can gradually lose mineral content and strength with age or certain health conditions, often without any symptoms appearing. A DEXA scan is the most commonly used test to detect low bone density, estimate fracture risk, and track changes over time when interpreted alongside clinical risk factors[1]. This article explains what a DEXA scan is, how it works, who should consider one, what the results mean, and how to protect your bone health after testing.
What is a DEXA Scan and How Does it Measure Bone Density?
A DEXA scan, also written as a DXA scan, is a low-dose X-ray test that measures how dense and strong your bones are. It is most commonly performed on the hip and spine, as these are the sites most likely to fracture when bone density is low.
The scan uses two different X-ray energy levels. Software analyses the images and subtracts soft tissue such as muscle and fat, leaving a calculation of bone mineral density (BMD) alone[2]. This two-energy approach makes it more precise than a regular X-ray for measuring bone strength.
A regular X-ray can show obvious fractures or severe bone loss, but it is not sensitive enough to detect early or moderate reductions in bone density. Central DEXA is the established standard for measuring BMD and estimating the risk of fractures. Peripheral devices and some ultrasound-based tools are mainly used for screening in certain settings and are less reliable for confirming a diagnosis or monitoring treatment[3].
DEXA Scan, Bone Density Test, and BMD Test: are They the Same?
These three terms are often used interchangeably, and that can create confusion. Here is what each one means:
Bone density test: A general term for any test that measures the amount of mineral in your bones, which reflects bone strength.
BMD test: Short for bone mineral density test, this is the broader category of tests that assess bone mineral content.
DEXA scan or DXA scan: The specific technology most commonly used to perform a BMD test.
Because DEXA is the most widely used and most accurate bone density scan, the terms "bone density test", "BMD test", and "DEXA scan" are frequently used to mean the same thing in clinical practice[4]. If your doctor recommends a BMD test, a DEXA scan is typically what will be arranged.
When to Get a DEXA Scan: Signs, Risk Factors, and Age-Based Recommendations
The Indian Menopause Society's Clinical Practice Guidelines on Postmenopausal Osteoporosis recommend opportunistic osteoporosis screening for women older than 40 years, based on evidence that low bone mass affects more than 40% of women from age 40 and over 80% by age 65, with accelerated bone loss during the first five years after menopause and an early age of fracture presentation[5].
Risk-based testing is commonly considered for people with[5]:
Low body weight
A previous fracture after minor trauma
Parental history of hip fracture or osteoporosis
Current smoking or excess alcohol use
Rheumatoid arthritis or other chronic conditions
Long-term corticosteroid use
Suspected low BMD in younger adults
The burden of bone loss in India is significant. A review found a pooled osteoporosis prevalence of about 29% at both the lumbar spine and femoral neck among postmenopausal Indian women[6]. This underscores the importance of timely bone density testing, particularly for women in this group.
Consult your doctor to determine whether a DEXA scan is appropriate based on your individual health history.
What Happens During a DEXA Scan?
Preparation for a DEXA scan is minimal. You may be asked to avoid calcium supplements for about 24 to 48 hours before the test and to remove metal objects such as jewellery. Clothing with metal fasteners should be avoided[4].
During the scan, you will lie on a padded table while a scanning arm passes slowly over your hip and spine. The procedure typically takes around 10 to 30 minutes. You do not need to enter a tunnel or enclosed space, which many people find more comfortable than other imaging tests.
A DEXA scan is quick, painless, and non-invasive. It uses very low-dose ionising radiation. If you are or may be pregnant, you should inform the radiographer before the scan, as the test is generally deferred unless it is clearly necessary[3].
Understanding Your Bone Density Test Results
After a bone density test, results are reported as two scores[1]:
T-score: Compares your bone density with that of a healthy young adult of the same sex. This score is mainly used for postmenopausal women and men aged 50 or older.
Z-score: Compares your bone density with that of people of the same age, sex, and body size. This score is more commonly used for younger adults and children.
The table below shows how T-scores are interpreted:
Result | T-Score | What It Means |
|---|---|---|
Normal | -1.0 or higher | Bone density is in the expected range |
Osteopenia | -1.0 to -2.4 | Low bone density; higher future fracture risk |
Osteoporosis | -2.5 or lower | Bone density meets the osteoporosis threshold |
A T-score alone does not tell the full story. Your doctor will also consider your age, fracture history, and other risk factors when interpreting your result[4].
What Can Affect Bone Density Over Time?
Several factors can cause bone density to decline over the years[7]:
Ageing: Bones naturally become less dense as you get older.
Hormonal changes: Menopause and other hormonal shifts can accelerate bone loss.
Low calcium or vitamin D intake: Inadequate nutrition can weaken bones over time.
Smoking and excess alcohol: Both smoking and alcohol are associated with lower bone density.
Physical inactivity: Lack of weight-bearing activity may reduce bone strength.
Chronic illnesses: Conditions such as rheumatoid arthritis can affect bone health.
Long-term medicines: Glucocorticoids (steroids) taken over extended periods may reduce bone density.
Understanding these risk factors can help you and your doctor decide how frequently bone health should be monitored.
Protecting Your Bones After a Bone Density Test
After a bone density test, your doctor may suggest a range of steps depending on your results. These can include[7]:
Nutrition: Ensuring adequate calcium and vitamin D through diet or supplementation as advised by a clinician.
Exercise: Weight-bearing and resistance exercises may help maintain or improve bone strength.
Lifestyle changes: Reducing smoking and alcohol consumption.
Fall prevention: Taking measures at home and in daily life to lower the risk of falls and fractures.
Follow-up scans: Repeat scanning may be recommended based on your fracture risk, treatment status, and original result.
Prescription treatment: If osteoporosis is confirmed or fracture risk is high, your doctor may discuss medication options.
It is also worth noting that DEXA interpretation can be affected by spinal changes, previous spinal surgery, vertebral fractures, or hip replacements. In such cases, an alternative scanning site such as the forearm may be used[8].
Treatment must be determined by a healthcare provider.
Key Takeaways
- A DEXA scan is the standard low-dose test for measuring bone mineral density, most commonly at the hip and spine.
- Screening is recommended for postmenopausal women, with opportunistic screening in Indian women considered from age 40 due to earlier bone loss patterns and fracture risk. Older women and those with additional risk factors should be prioritised for evaluation.
- Results are mainly interpreted through T-scores: a score of -1.0 or higher is normal, -1.0 to -2.4 indicates osteopenia, and -2.5 or lower indicates osteoporosis.
- Bone health after testing relies on addressing risk factors, staying active, eating well, preventing falls, and following up with your doctor when needed.
FAQs
Is a DEXA scan painful?
No, a DEXA scan is painless and non-invasive. You simply lie on a padded table while the scanner passes over the hip and spine. There are no injections, no enclosed spaces, and no discomfort involved. Most people find it straightforward and quick.
How often should a bone density test be repeated?
Repeat timing depends on your baseline result, fracture risk, treatment status, and your doctor's clinical judgement. Some people at higher risk may be advised to retest around every two years. Your doctor is best placed to advise on the right interval for you.
Do younger adults need a BMD test?
Yes. BMD testing is not limited to older adults. In India, opportunistic screening may be considered for women above 40 years, especially after menopause, due to the higher risk of early bone loss. Younger adults may also need a DEXA scan when risk factors such as chronic diseases, long-term glucocorticoid therapy, premature menopause, or previous fragility fractures are present.
Do I need to stop taking calcium supplements before a DEXA scan?
Usually yes. You may be asked to stop calcium supplements for around 24 hours before the scan. Always follow the specific instructions given by your test centre or doctor, as guidance can vary slightly between facilities.
Can a bone density test detect osteoporosis before symptoms appear?
Yes. One of the main purposes of a DEXA scan is to detect low bone density and estimate fracture risk before symptoms such as pain or fractures develop. Early detection allows for timely intervention and monitoring.
Does health insurance usually cover a DEXA scan?
Coverage varies widely depending on your insurer, policy type, indication for the scan, hospital network, and whether a prescription is required. It is advisable to check directly with your insurance provider before booking the test.
Can pregnancy affect whether a DEXA scan is recommended?
Yes. Because a DEXA scan uses low-dose ionising radiation, it is generally deferred during pregnancy unless it is clearly necessary for clinical reasons. Always inform your doctor or radiographer if you are or may be pregnant before the scan is performed.
Can I have a DEXA scan if I have a hip or spine implant?
Often yes, but implants, previous spinal surgery, or significant spinal changes can affect how results are interpreted. In such cases, an alternative site such as the forearm may be scanned instead. Discuss your implant history with your doctor before booking.
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. The information provided should not be used for diagnosing or treating health conditions. Always consult a qualified healthcare provider for diagnosis, treatment, and personalised medical advice. Do not disregard professional medical advice or delay seeking it because of information found in this article. If you have a medical emergency, contact your doctor or emergency services immediately.
References
NIAMS/NIH. (2025). Bone Mineral Density Tests: What the Numbers Mean. National Institute of Arthritis and Musculoskeletal and Skin Diseases. https://www.niams.nih.gov/health-topics/bone-mineral-density-tests-what-numbers-mean
CDC. (2025). Facts About Bone Density (DEXA Scan). Centers for Disease Control and Prevention. https://www.cdc.gov/radiation-health/data-research/facts-stats/dexa-scan.html
RadiologyInfo/ACR-RSNA. (2024). Bone Density Scan (DEXA or DXA). RadiologyInfo.org. https://www.radiologyinfo.org/en/info/dexa
NLM MedlinePlus. (2024). Bone Density Scan. MedlinePlus. https://medlineplus.gov/lab-tests/bone-density-scan/
