Paget's disease. A cause of artificially elevated bone mineral density.

A 48-year-old man with a ten-year history of corticosteroid-dependent asthma and a previous fracture of the right humerus after minimal trauma was referred for a dual photon absorptiometry (DPA) study to assess the degree of osteoporosis. The DPA study revealed a large discrepancy in bone mineral density (BMD) between the right and left hips. A Tc-99m MDP bone scan and an anteroposterior frog-leg radiograph demonstrated changes typical of Paget's disease in the sacrum, pelvis, and femurs. This case is an example of how underlying bone disease may artificially elevate bone mineral density, and demonstrates the value of performing BMD tests on both hips and the necessity for correlative bone scans and radiographs in selected cases.