Diagnostic challenges in osteoporosis. Indications for bone densitometry and establishing secondary causes

To review indications for assessing bone mineral density (BMD) and to review patient characteristics and diseases associated with osteoporosis.

This paper is based on data from longitudinal observational studies of how BMD and other risk factors affect development of fragility fractures and on several peer-reviewed publications describing pathophysiology of bone turnover and pathogenesis of osteoporosis. Indications for obtaining BMD and monitoring treatment are based on the recommendations of the Osteoporosis Society of Canada derived from the consensus opinion of a panel of experts in osteoporosis and based on their review of the primary literature.

Measurement of BMD provides the best single objective predictor of the relative risk of fracture at sites such as the vertebrae, hip, and wrist, predicting the likelihood of fracture with as much accuracy as measurement of elevated blood pressure predicts stroke. In addition to making the diagnosis of osteoporosis, BMD measurements are used to monitor progression of osteoporosis and effects of therapy. At this date, dual energy x-ray absorptiometry is preferred for measuring BMD. The most likely causes of osteoporosis in any patient are age, hormone withdrawal (in both men and women), and drugs (particularly corticosteroids). Secondary causes, particularly hyperparathyroidism and multiple myeloma, should be excluded by performing appropriate laboratory tests.

A BMD measurement should be obtained for patients at high risk of osteoporosis and fragility fractures to guide initiation and monitor success of therapy.