Higher Serum Uric Acid Levels in Multiple Sclerosis Patients After Longterm Interferon Beta Treatment

Interferon beta is a safe and efficacious treatment for relapsing multiple sclerosis (MS). However, there is some evidence that uric acid, a scavenger of peroxynitrite, is involved in MS pathology and that increasing serum uric acid levels might have beneficial therapeutic effects. The aim of this study is to investigate serum uric acid levels in MS patients before and after long-term interferon beta treatment. Blood samples from 101 MS patients (53 receiving interferon beta 1a treatment and 48 receiving interferon beta 1b treatment; 28 male and 73 female; mean age at treatment onset 32,4±7,3 years; mean duration of disease at treatment onset 5,1±3,2 years; mean EDSS 2±1,3) before and after interferon beta treatment (mean treatment duration 3±2 years) were analysed. Serum uric acid levels were measured using a quantitative enzymatic assay (Elitech Diagnostic, Sees, France). MS patients had significantly increased serum uric acid levels after treatment compared with those at the beginning of treatment (272,31±78,21 μmol/l vs. 210,17±53,65 μmol/l; p=0,019, Wilcoxon Mann-Whitney U-test). We did not find significant differences in serum uric acid levels between the interferon beta 1a and interferon beta 1b groups (p=0.98). These results indicate that one of the beneficial effects of interferon beta in MS might be based on the elevation of serum uric acid levels as a natural scavenger of peroxynitrite.