Bone density screening identifies low bone mass before fractures occur and guides prevention or treatment of osteoporosis. The standard test is dual-energy X-ray absorptiometry (DXA) of the hip and spine, which yields a T-score used worldwide to classify bone health. The World Health Organization established the T-score threshold for osteoporosis as -2.5 or lower, a benchmark still used in clinical practice to predict fracture risk.
Who should be screened?
Clinical guidelines emphasize screening for older women. The U.S. Preventive Services Task Force recommends bone density testing for women aged 65 years and older and for younger women whose fracture risk is equal to or greater than that of a 65-year-old woman without additional risk factors. Evidence remains limited for routine screening of men, and decisions for men are often individualized according to clinical judgment and risk factors. To estimate individual fracture probability clinicians commonly use risk tools such as FRAX, developed by John A. Kanis University of Sheffield, which integrates age, body mass, prior fractures, medication use, and other variables to guide whether DXA is indicated.
When to start and how often to test
The age-based starting point protects many older women at higher risk, but earlier testing is appropriate for adults with strong risk factors. Major contributors to accelerated bone loss include long-term glucocorticoid treatment, history of fragility fracture, premature menopause, low body weight, chronic inflammatory disease, malabsorption, excessive alcohol use, and tobacco exposure. Populations with limited access to calcium-rich diets, low vitamin D exposure, or reduced opportunities for weight-bearing activity face higher lifetime risk, so social and environmental context matters when timing screening.
Frequency of repeat DXA is individualized. Monitoring intervals depend on baseline bone density, ongoing risk exposures, and whether pharmacologic therapy is initiated. Many clinicians reassess during the first one to three years after a treatment change or when rapid bone loss is suspected, and extend intervals when bone density is stable and risk factors are controlled.
Causes and consequences
Bone density reflects a lifetime balance between bone formation and resorption. Age-related decline, hormonal changes after menopause, nutritional deficits, chronic disease, and medications can tip this balance toward bone loss. The clinical consequence of undiagnosed low bone mass is increased risk of fragility fractures—particularly of the hip, spine, and wrist—which are associated with pain, disability, loss of independence, and increased mortality in older adults.
Practical approach
Discuss screening with a primary care clinician or specialist who can apply risk calculators and local guidelines. DXA is widely available in hospitals and imaging centers and is quick, low radiation, and reimbursed in many systems when indicated. Prevention strategies following screening include lifestyle measures—adequate calcium and vitamin D, regular weight-bearing exercise, tobacco cessation—and medical therapy when fracture risk warrants it. Recognizing the influence of cultural, nutritional, and territorial factors on bone health helps clinicians tailor screening and prevention to each person’s circumstances.