Relationship between Bone Density and Biochemical Markers of Bone among Two Groups Taking Carbamazepine and Sodium Valproate for Epilepsy in Comparison with Healthy Individuals in Yazd.

Introduction: Chronic antiepileptic therapy has been associated with metabolic bone diseases including osteomalacia and osteoporosis. The aim of this study was to determine frequency of changes in biochemical and bone mineral density (BMD) in adults receiving valproaic acid (VPA) & carbamazepine (CBZ).

Methods: In a cross sectional study evaluating adults (age 20-50 y) epileptic patients receiving valproic acid or carbamazepine for at least 2 years. This study was conducted from May 2014 to May 2015 in Shahid Sadoughi Hospital of Yazd University of Medical Science, Yazd, Iran. Bone metabolism was evaluated by measurement of serum calcium (Ca), phosphorus (P), alkaline phosphatase (ALP) and parathormone hormone (PTH), BMD at lumbar and femoral measured by dual energy X ray absorptiometry (DXA). SPSS software (version 18) was used for data analysis. The t-test was used for quantitative data, and the chi-squared test was used for the qualitative variables.

Results: Eighty two epileptic patients (mean age: 31.67±10.69 year) treated with either carbamazepine (n=41) or valproate sodium (n=41) were studied. Normal serum Ca and P levels were observed in 98.8% and 97.6% of patients respectively. Serum ALP and PTH were normal in 97.6% and 97.6% of patients. Means of Ca and P in CBZ group were significantly lower than VPA group (Ca: 9.02 vs. 9.1, p-value: 0.03 and P: 3.54 vs. 3.76 p-value: 0.004). BMD values at lumbar spine were not significant in either group (T. score CBZ: -0.43± 0.744 vs. T. score VPA: -0.615± 0.904 and p-value: 0.333) and were significantly higher than Iranian normal population BMD value at femoral neck in CBZ group was lower than VPA group (T. score CBZ: -0.707± 0.896 vs. T. score VPA: - 0.297± 0.850 p-value: 0.04). Dosage of CBZ and VPA did not correlate with BMD and biochemical parameters. Duration of CBZ use had correlation with increased ALP and duration of VPA use had correlation with decreased BMD in adult patients.

Conclusion: long term anti-epileptic drug treatment either with CBZ and VPA which has unknown effects on skeletal mineralization and induces a state of decreased bone mineral density BMD values at femoral neck were significant in CBZ group Therefore regular screening for monitoring of biochemical markers of bone turnover and BMD with DXA during the treat period is recommended. In addition, Ca supplement could be considered for all patients with epilepsy upon initiation of CBZ and VPA therapy.