Bone Density of Ambulatory Adult Patients Receiving Long-term Anticonvulsant Drug Therapy

Chronic antiepileptic therapy has been associated with metabolic bone diseases including osteomalacia and osteoporosis. The object of this study was to assess the effect of first line anticonvulsants on bone density and vitamin D levels in Iranian ambulatory patients. We conducted a cross-sectional study assessing bone density with dual energy X-ray absorptiometry at the hip and lumbar spine in 90 outpatients receiving anticonvulsants and 90 normal subjects matched for age, sex, and body mass index. Plasma total calcium, intact parathyroid hormone, total alkaline phosphatase in addition to 25 hydroxy vitamin D were also determined in both groups. The mean (±SD) bone density in patients treated with antiepileptic drugs was lower at the spine (T Score= -084±1.18 vs. -0.5±1.18, P< 0.05) and femoral neck (T Score= -0.83±1.11 vs. -0.46±1.1, P<0.05), compared to the control group of subjects. In addition, serum total alkaline phosphatase was significantly higher in patients (246.5±127 vs. 190±65.3, P=0.004), but the total calcium, parathyroid hormone and 25 hydroxy vitamin D did not differ significantly between patients and controls. Our results suggest that maintenance therapy with antiepileptic drugs may decrease bone mass. These data also suggest a higher bone turnover rate in those receiving anticonvulsants.