DXA scans use low-dose X-rays to evaluate bone mineral density and estimate body composition. According to medical experts, the imaging tests are recommended for women aged 65 and older and men 70 and older, as well as younger adults with specific risk factors for fractures.
While often associated with older adults, dual-energy X-ray absorptiometry imaging has gained wider attention among younger populations curious about their personal fitness metrics. Beyond traditional bone health evaluations, the technology provides detailed insights into tissue distribution.
How DXA Scans Evaluate Bones and Body Composition
A DXA scan is an imaging test that uses low-dose X-rays to evaluate a person’s bone health, according to Dr Michael Perry, associate professor of radiology and medical imaging at the University of Virginia’s school of medicine. The procedure most frequently measures the strength and mineral content of bones in the hip and spine to determine an individual’s risk for osteoporosis and fractures.
During a procedure, a patient lies on a padded table while a scanning arm passes overhead, a process that typically takes 10 to 20 minutes. Medical experts describe the imaging as safe, quick and painless.
In addition to mineral density, the technology estimates body composition. According to Dr Ann Malbas, an endocrinologist at the Mayo Clinic who specializes in bone diseases, the scans measure fat percentage, muscle mass, and where fat is distributed throughout the body. The scanning procedure remains identical when measuring body composition rather than bone density, though it evaluates lean mass and total fat percentages instead.
Who Needs a DXA Scan and When
Medical guidelines establish clear parameters for routine bone density screening. According to Dr Shadpour Demehri, professor of radiology and radiological science at Johns Hopkins University’s school of medicine, DXA is recommended for women aged 65 and older and men ages 70 years and older, as well as younger adults who have important risk factors.
Those risk factors for low bone density include a previous broken bone from a minor fall or injury, long-term use of steroid medications such as prednisone, a family history of osteoporosis or hip fractures, and underlying conditions like chronic obstructive pulmonary disease.
Physicians emphasize routine monitoring for vulnerable groups because osteoporosis functions as a silent condition. Patients frequently remain unaware of the disease until an impact causes a fracture. Data indicates that osteoporotic fractures affect one in three women and one in five men over the age of 50.
Safety Considerations and Limitations
Although the examination utilizes minimal radiation, medical professionals note specific exclusions. Pregnancy generally requires postponing the examination because the procedure involves ionizing radiation. Furthermore, patients who recently underwent imaging tests involving contrast materials, such as barium studies, must delay their appointments because these substances interfere with diagnostic accuracy.
While younger individuals frequently request scans out of curiosity regarding body fat distribution, routine scans provide limited utility for this demographic. Demehri notes that routine evaluations for younger adults are unlikely to provide information that changes medical care.
Body Composition Versus Overall Weight
For individuals tracking fitness metrics, body composition imaging offers a more precise health snapshot than standard scales. Traditional body weight measurements account only for total tissue mass rather than distinguishing tissue types.
“Someone may fall into the overweight category but may have large amounts of muscle but very little fat. Conversely, a person with very low muscle mass may be at higher risk for falls and illness despite being ‘normal’ weight.”
Dr Michael Perry, associate professor of radiology and medical imaging at the University of Virginia’s school of medicine
Management Strategies for Low Bone Density
Related reading
