Lexicon
DEXA Scan
Also known as DXA, Dual-energy X-ray absorptiometry
Definition
Bone mineral density measurement by dual-energy X-ray absorptiometry (DXA) is the most commonly used method to assess fracture risk. [1] The introduction of DXA technology in the 1980s revolutionized the diagnosis, management and monitoring of osteoporosis, providing a clinical tool that is now available worldwide. [2] Central DXA measurement is the gold standard for determining bone mineral density. [3]
How it works
DXA utilizes two different-energy X-rays to calculate bone mineral density and, by comparison to a young normative database, the T-score. [1] For every standard deviation decline in bone mineral density measured by DXA there is a relative risk of 1.5 to 2.5 for fracture, a predictive ability comparable to how blood pressure predicts myocardial infarction. [1] DXA has low radiation exposure and wide availability, but bone mineral density can be affected by positioning errors or artifacts including osteoarthritis, fracture, and jewelry. [1]
Connected concepts
How it's measured
The recommended site for diagnosis is the proximal femur measured with DXA, and the same absolute bone mineral density value used in women can be used in men. [4] The proposed reference standard is bone mineral density measured at the femoral neck with DXA, using the NHANES III reference database for women aged 20 to 29 years. [5] T-scores are determined by DXA by comparing bone mineral density to young-adult standards, and DXA is also used as a body-composition technique alongside methods such as bioelectrical impedance analysis, computed tomography, and MRI. [6] [7]
What levels mean
Osteoporosis is defined as a bone mineral density 2.5 standard deviations or more below the average value for premenopausal women, that is a T-score below -2.5, and severe osteoporosis denotes osteoporosis in the presence of one or more fragility fractures. [4]
Community knowledge
## Clinical Use In Practice uses DEXA -- or an InBody impedance device where available -- to obtain objective percent-body-fat,…
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- 1.Jain RK, Vokes T. Dual-energy X-ray Absorptiometry. J Clin Densitom · 2017
- 2.Slart RHJA, Punda M, Ali DS, Bazzocchi A, Bock O, Camacho P, Carey JJ, Colquhoun A. Updated practice guideline for dual-energy X-ray absorptiometry (DXA). Eur J Nucl Med Mol Imaging · 2025
- 3.Anam AK, Insogna K. Update on Osteoporosis Screening and Management. Med Clin North Am · 2021
- 4.Kanis JA. Diagnosis of osteoporosis and assessment of fracture risk. Lancet · 2002
- 5.Kanis JA, McCloskey EV, Johansson H, Oden A, Melton LJ, Khaltaev N. A reference standard for the description of osteoporosis. Bone · 2008
- 6.Sangondimath G, Sen RK, T FR. DEXA and Imaging in Osteoporosis.
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