Variation of serum uric acid levels in multiple sclerosis during relapses and immunomodulatory treatment

Uric acid (UA), a product of purine metabolism, may be an antioxidant, perhaps acting as a scavenger of peroxynitrite. Patients with gout have a reduced incidence of multiple sclerosis (MS). A number of studies found that patients with MS have low serum levels of UA, although it has not been established whether this represents a primary deficit or a secondary effect. UA has also been proposed as a marker of disease activity and response to immunosuppressive or immunomodulatory treatment. We retrospectively reviewed 83 relapsing-remitting or secondary progressive MS patients (64 females and 19 males) followed in our Neurology Unit. We collected data concerning demographic variables as age and sex, and clinical variables as age of onset, clinical type, disease duration, EDSS score and total number of relapses. We considered UA levels in three different situations: during a relapse, during remission period and during remission period under immunomodulatory treatment [Interferon Beta 1a i.m. (Avonex; Biogen Idec Inc., Cambridge, MA, USA), Interferon Beta 1a s.c. (Rebif; Serono Europe Limited, London, UK), Interferon Beta 1b (Betaferon; Bayer Schering Pharma AG, Berlin, Germany) or Glatiramer Acetate (Copaxone; TEVA Neuroscience LLC, Kansas City, MO, USA)]. A Wilcoxon matched pairs test was carried out to determine differences between groups. A P-value less than 0.05 was considered statistically significant. In 33 patients, we were able to compare at least one UA value obtained during a relapse with at least one when remission without treatment. Mean serum UA levels were significantly lower when measured during a relapse (r: 0.39, P: 0.024). In 27 cases, we compared at least one remission value without treatment with at least one obtained during remission and immunomodulatory treatment. Mean serum UA levels significantly increased when determined during Interferon Beta or Glatiramer Acetate therapy (r: 0.84, P < 0.001). Although we do not know exactly whether and how UA is involved in MS pathogenesis, our data suggest that UA might reflect disease activity or treatment response in MS.