High-dose methylprednisolone therapy in multiple sclerosis increases serum uric acid levels

Uric acid, which is the final product of purine nucleoside metabolism, is a strong peroxynitrite scavenger. Several studies report on lower serum uric acid levels in multiple sclerosis. In this study, we investigated serum uric acid levels before and after high-dose methylprednisolone treatment (intravenous 1 g/day/5 days) in multiple sclerosis patients. Blood samples from 25 definite multiple sclerosis patients (11 male and 14 female) before and after methylprednisolone treatment (days 0, 6 and 30) and from 20 healthy donors (9 male and 11 female) were analyzed. Serum uric acid levels were measured using a quantitative enzymatic assay (Elitech diagnostics, Sees, France) according to the manufacturer's protocol, and the results were standardized using a commercial uric acid standard solution. We observed significantly increased serum uric acid levels 1 day after the termination of the therapy (day 6). These differences were sustained for 30 days after starting treatment (during remission period). Mean serum uric acid levels were significantly higher in the control group. These results suggest that increasing the uric acid concentration may represent one of the possible mechanisms of action of methylprednisolone in multiple sclerosis.