Diagnostics
Bone density test (DEXA SCAN)
What is a DEXA scan?
Who performs the DEXA scan?
Why is a bone density test performed?
A bone density test is commonly performed to:
- Diagnose osteoporosis: It helps diagnose osteoporosis, a condition characterized by weakened and brittle bones that are more prone to fractures.
- Assess fracture risk: The test assesses the risk of fractures, helping doctors develop appropriate prevention and treatment plans.
- Monitor bone health: It can be used to track changes in bone density over time and evaluate the effectiveness of osteoporosis treatments.
Who gets a DEXA Scan?
The doctors commonly recommend a DEXA scan to assess bone health, osteoporosis risk, and fracture susceptibility. It is often advised for individuals over 50 years old, those with a history of fractures, and those with conditions that increase the risk of bone loss.
Women are typically advised to undergo DEXA scans at younger ages than men due to research showing earlier and faster bone mass loss in women.
The doctors may recommend a DEXA scan if an individual has one or more risk factors, including:
- Increased age: Bone mass loss is common as people age, with DEXA scans recommended around 65 for women and 70 for men.
- Family history: Having family members with osteoporosis or a history of fractures can elevate risk.
- Previous fractures: Breaking a bone, especially after 50, may indicate increased fracture risk due to porous (less dense) bones.
- Medications: Certain medications, such as prednisone, cancer drugs, or post-transplant medications, can weaken bones.
- Chronic medical conditions: Disorders like rheumatoid arthritis, lupus, diabetes, liver disease, and kidney disease can contribute to bone fragility.
How is a bone density test conducted?
Preparing for a bone density test
Patients are typically not required to undertake any specific preparations for a DEXA (Dual-Energy X-ray Absorptiometry) scan unless otherwise instructed by their doctor. Standard daily activities, including eating, drinking, and taking medications, can continue as usual. The technologist should be informed if the patient is pregnant or has recently undergone other radiology exams involving contrast materials.
Patients will be asked to wear loose-fitting attire without metal components like buttons or zippers. In some cases, they may be provided with a hospital gown to wear during the procedure, as metal objects can interfere with the accuracy of the scan.
During the test
- The patient will lie down on a cushioned table, typically in a supine position (on their back). The specific region of interest, such as the hip or spine, will be centered within the DEXA scanner.
- The DEXA machine emits a minimal amount of X-ray radiation to capture images of the bone at different energy levels.
- The scanner collects the measurements of bone density and translates the data into images and graphs. Bone appears white, while fat and muscle tissue appear as shadows on the technologist’s computer monitor.
- The DEXA scan results are reviewed and interpreted by a radiologist or other physician with expertise in DEXA interpretation. They analyze the images and data to evaluate bone density and assess bone health. The quick test takes about 10 to 30 minutes to complete.
- A written report is generated and sent to the doctor.
Results are reported in the form of a T-score, which compares bone density to that of a healthy young adult of the same sex.
References
- Mayo Clinic. Bone Density Test. Available from: https://www.mayoclinic.org/tests-procedures/bone-density-test/about/pac-20385273
- Cleveland Clinic. DEXA (DXA) Scan: Bone Density Test. Available from: https://my.clevelandclinic.org/health/diagnostics/10683-dexa-dxa-scan-bone-density-test
- How it is performed. Bone density scan (DEXA SCAN). Available from: https://www.nhs.uk/conditions/dexa-scan/what-happens/
