Evaluation and measurement of bone mass.

Patients taking antiepileptic drugs (AEDs) have an increased risk for osteoporosis and osteoporotic fractures. Bone mineral density (BMD) is the best predictor of fracture risk. Measurement of BMD allows the identification of patients at risk before they suffer a fracture. The current "gold standard" for the measurement of BMD and diagnosis of osteopenia and osteoporosis is dual-energy X-ray absorptiometry. Clinicians should be familiar with the ways in which bone mass measurements are reported and should understand how to use BMD measurements in making treatment decisions and monitoring treatment. They should also be aware of current controversies, including the role of peripheral versus central BMD measurements and the use of different reference databases for different patient groups. Laboratory assessment to identify secondary causes of osteoporosis, such as low vitamin D status in patients taking AEDs, is useful, but the role of markers of bone turnover in clinical practice has not been well defined.