Phenytoin-induced changes in the bone mineral metabolism in young males

Abstract

Background: Antiepileptic drugs (AEDs) have an adverse effect on the bone mineral metabolism. Patients and Methods: The objective of the study was to determine the bone loss and change in bone mineral parameters in patients treated with phenytoin sodium. We prospectively studied 36 young males aged 20–30 years, with new-onset epilepsy, and treated with phenytoin. Patients were clinically examined and subjected to determination of the bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) at the femur neck, spine, and lower third of radius. We also assessed Vitamin 25-OH-Vitamin D3, parathyroid hormone (PTH), and osteocalcin at the onset and after 1 year of treatment. Results: There were no significant changes noted in the 25-OH-Vitamin D3, (20.7 ± 10 ng/dl before and 18.5 ± 7.3 ng/dl after therapy, P = 0.198), and serum parathyroid levels (8.8 ± 6.8 pg/ml before and 14.2 ± 11.5 pg/ml, P = 0.114) at the end of 1-year therapy. There was declines in BMD at all the three sites; the spine (0.943 ± 0.11 vs. 0.943 ± 0.12 g/cm2, P = 0.15), femur neck (0.912 ± 0.0.12 vs. 0.896 ± 0.124 g/cm2, P = 0.093), and a statistically significant decline lower third of radius (0.659 ± 0.07 vs. 0.644 ± 0.073 g/cm2, P ≤ 0.001). We did not find any significant change in levels of 25-OH-Vitamin D3, PTH, and serum alkaline phosphatase, but found significant elevation in levels of osteocalcin. Conclusions: Phenytoin therapy in young male patients for 1-year causes a bone loss at femur and spine in the absence of Vitamin D deficiency and significant bone loss in the cortical bone radius. DXA should be done in patients during the treatment with AEDs to identify patients who are susceptible to increased risk of fractures.