Serum and erythrocyte membrane sialic acid levels in patients with rheumatoid arthritis and ankylosing spondylitis and a methodological evaluation

Abstract

Objectives: Aim of this study was to investigate serum and erythrocyte membrane total sialic acid levels in patients with rheumatoid arthritis and ankylosing spondylitis and demonstrate any correlation between total sialic acid and disease activity score and other inflammation variables. Material and methods: Serum total sialic acid and erythrocyte membrane sialic acid levels were measured in 24 rheumatoid arthritis, 19 ankylosing spondylitis patients and 24 healthy controls as well as serum C-reactive protein, anticyclic citrullinated peptide, rheumatoid factor, alkaline phophatase and erythrocyte sedimentation rate and compared with activity of the diseases. Results: Serum total sialic acid levels of patient groups were statistically higher than control group (p<0.05). Serum total sialic acid levels in rheumatoid arthritis were significantly higher than the ankylosing spondylitis patients (p<0.05). There was no significant difference between the groups for erythrocyte membrane sialic acid. Significant correlation was found between serum total sialic acid and serum C-reactive protein in both groups (r=0.411, r=0.825); correlation between serum total sialic acid and erythrocyte sedimentation rate was found only in ankylosing spondylitis group (r=0.515). There was a significantly negative correlation between erythrocyte membrane sialic acid and serum C-reactive protein in ankylosing spondylitis group (r =-0.570). Conclusion: Serum total sialic acid is a useful diagnostic tool as an inflammatory parameter and can be used in the differential diagnosis of rheumatoid arthritis and ankylosing spondylitis.