Bone Metabolism In Ambulatory, Premenopausal Women Using Antiepileptic Drugs, Attending The Neurology Clinic At The Kenyatta National Hospital

Abstract

BACKGROUND Long term antiepileptic drug use causes multiple abnormalities in calcium and bone metabolism that have been described in both institutionalized and ambulatory patients, in the Western set-up. On average at Kenyatta National Hospital, 30 to 35% of the total numbers of patients seen weekly at the Neurology clinic are women with epilepsy. RATIONALE Exposure to anti-epileptic drugs puts women at a higher risk for osteoporosis, before they reach menopause. No studies have been published locally to describe the effect of long term AED use on women's bone health. OBJECTIVE The broad objective of this study was to assess bone metabolism in ambulatory females of reproductive age on antiepileptic drugs, at KNH. METHODS This was a cross-sectional comparative study that explored the relationship between Bone health and long-term treatment with anti epileptic drugs in women of reproductive age. Fifty seven women on drugs for more than 1 year were compared with 53 age-matched controls. Biochemical markers of bone metabolism were measured, namely serum Calcium, Phosphate, Alkaline Phosphate and Urinary Calcium Excretion. Bone Mineral Density

measurement at the Lumbar Spine was undertaken on a limited number of subjects due to financial constraints. (24 patients and 24 controls) Patients were, as closely as possible, matched for age, weight and height with an otherwise healthy control. RESULTS The mean duration of treatment for epilepsy was 8.8years (±6.3). Majority of the patients were on enzyme inducing drugs, either alone or in combination with non-enzyme inducers (98.2%). There was a significantly lower mean serum calcium and a higher alkaline phosphatase level among the patients (P=0.002 and 0.0001 respectively) than among the controls. The urinary marker of bone loss (mean Urine calcium excretion) was also significantly raised among the patients (P=0.003). The mean Lumbar BMD T-score results were not significantly different in the two groups.

CONCLUSION Long-term antiepileptic drug use significantly affects biochemical parameters of bone metabolism. These effects on bone biochemistry markers were not reflected in Lumbar spine BMD RECOMMENDATIONS Further studies with larger sample sizes are required to fully elucidate the impact of AEDs on bone metabolism. Health care workers should be aware of the possible side effects of AEDs on bone health; especially as regards women, who are prone to age-related osteoporosis.