Practical use of bone densitometry

Dual energy x-ray absorptiometry (DXA) is currently the best clinically available tool for diagnosing decreased bone mineral density before osteoporotic fractures occur. The recent introduction of new treatment options for osteoporosis makes accurate and early diagnosis more important than in the past. Some women lose bone at the rate of 3-5% per year in the years immediately after menopause. DXA allows early identification of individuals at risk of fracture when osteoporosis is still asymptomatic. In epidemiologic studies, each standard deviation decrease in bone mineral density at the hip is associated with an approximately 2.5-fold increase in the risk of hip fracture. The average 50-year-old woman has an approximately 40% chance of suffering one or more fragility fractures during her lifetime. DXA allows identification of individuals at risk. Insurance coverage of DXA remains variable among insurers and accepted indications are limited. This report describes some pitfalls in practical use of DXA scans, current definitions used in reporting, and provides suggestions on when DXA scans should be done.