Effect of long-term valproate monotherapy on bone mineral density in adults with epilepsy

Background: We evaluated the cross-sectional relationship of duration and dosage of valproate monotherapy on bone mineral density (BMD) in adult patients with epilepsy. Methods: The BMD at lumbar level (L2-L4) was measured in consecutive adult epileptic patients receiving long-term (>= 2 years) valproate monotherapy by dual energy X-ray absorptiometry (DXA). Blood samples were collected for total serum calcium, phosphorus, magnesium, 25-hydroxyvitamin D-3 and parathormone. Osteopenia and osteoporosis were defined according to the World Health Organization operational BMD definition. Cross-sectional associations were evaluated using Spearman's correlation coefficient. Results: A total of 41 patients were studied (mean age 32.3 +/- 8.2 years, 12 men, mean duration of valproate monotherapy 10.6 +/- 7.4 years). Osteopenia was present in 24% of subjects, while no case of osteoporosis was documented. Duration and dosage of valproate monotherapy did not correlate with BMD. No association was documented between duration or dosage of valproate monotherapy and biochemical parameters. Conclusions: Duration of valproate monotherapy does not correlate with decreased BMD in adult patients with epilepsy. No case of osteoporosis was identified in patients treated with valproate for a mean period of more than ten years. These findings indicate that bone metabolism may not be affected by valproate monotherapy. (C) 2009 Elsevier B.V. All rights reserved.