A Dual-Energy X-ray Absorptiometry (DEXA) scan is a non-invasive imaging test that uses low-dose X-rays to determine your bone mineral density (BMD), primarily in the hip and spine. Measuring BMD is the standard method for diagnosing conditions like osteoporosis and osteopenia, which involve weakened bone structure. Since bone loss often progresses without noticeable symptoms, the timing of this scan is a significant factor in preventing fractures and guiding treatment.
Standard Age Guidelines for Bone Health Screening
General screening guidelines for bone health are established for individuals who do not have specific risk factors. For women, the consensus recommendation is to begin routine DEXA screening at age 65, as the risk of fracture significantly increases after this point. The U.S. Preventive Services Task Force (USPSTF) advises screening women aged 65 years and older to prevent osteoporotic fractures. This threshold is based on population data that show the most benefit for asymptomatic individuals in this age group.
Men are advised to begin screening at age 70. Although men also experience age-related bone loss, the progression tends to be slower than in women, leading to this later screening benchmark. These age-based guidelines are designed to identify low bone density early enough to intervene effectively with lifestyle changes or medication.
Screening can start earlier for women under the age of 65 if their fracture risk is comparable to that of an average 65-year-old woman. This assessment often uses clinical tools that consider factors like body weight, current smoking status, or a parent’s history of hip fracture. By evaluating these risk factors, healthcare providers can determine if bone density testing should be initiated earlier than the standard age threshold.
Medical Conditions Requiring Earlier DEXA Testing
Certain medical conditions and medications can accelerate bone loss, necessitating a DEXA scan before the standard age recommendations. A history of a fragility fracture—a break resulting from a fall from a standing height or less—is a strong indication for immediate testing, regardless of age, to diagnose underlying low bone mass. Similarly, a very low body weight (Body Mass Index (BMI) below 21 or a body weight less than 127 pounds) places an individual at higher risk for osteoporosis and warrants earlier screening.
Chronic inflammatory diseases like rheumatoid arthritis are linked to bone loss due to the disease process itself and the treatments often used. Conditions that impair nutrient absorption, such as Celiac disease or Crohn’s disease, can also lead to osteoporosis by limiting the body’s uptake of calcium and Vitamin D. Patients with chronic kidney disease or chronic liver disease are also prone to bone density issues that require monitoring through early DEXA testing.
Long-term use of prescription medications prompts earlier screening. Glucocorticoids, often prescribed for inflammatory or autoimmune conditions, can be toxic to bone tissue, particularly when taken for three months or longer. Other medications, including some anti-seizure drugs, aromatase inhibitors used in breast cancer treatment, and hormone-suppressing therapies, are known to negatively impact bone mineral density.
Specialized Use in Children and Adolescents
DEXA scans are not a routine screening tool for children and adolescents, but they are used in specialized clinical settings to monitor bone health in individuals with specific medical concerns. The scan is typically reserved for those with a history of multiple low-trauma fractures or chronic diseases that interfere with peak bone mass accrual. The diagnosis of osteoporosis in a child requires both a history of fractures and a finding of low bone density.
Unlike adult scans, which use T-scores compared to a young, healthy adult reference population, pediatric DEXA results are interpreted using Z-scores. The Z-score compares the child’s bone density to that of other children of the same age, sex, and ethnicity. This adjustment is necessary because children’s bones are still growing, making the adult T-score standard inappropriate for accurate assessment.
Clinical indications for pediatric DEXA include monitoring the effects of severe chronic conditions or evaluating bone density in children receiving long-term treatment with glucocorticoids or those experiencing prolonged immobilization. These scans focus on the lumbar spine and the total body (excluding the head) to track changes in bone density over time and assess intervention effectiveness.
Conditions Requiring Pediatric DEXA
- Osteogenesis imperfecta
- Cystic fibrosis
- Inflammatory bowel disease
- Prolonged immobilization