Comparison of adenosine deaminase levels in serum and synovial fluid between patients with rheumatoid arthritis and steoarthritis

Objectives: Adenosine deaminase (ADA) is an enzyme being involved in purine metabolism and plays a significant
role in the immune system. The aim of this study was to investigate the use of adenosine deaminase levels in
differentiating between rheumatoid arthritis and osteoarthritis. Material and methods: Thirty patients with rheumatoid
arthritis and 30 osteoarthritis patients enrolled the study. They were matched in sex and age. Using the ROC
curve, we determined the optimal serum and synovial cutoff for rheumatoid effusion. Results: The results showed a
statistically significant difference between ADA levels in joint effusion and serum of patients with rheumatoid arthritis
and osteoarthritis (p<0.001). Synovial fluid cutoff value for diagnosing rheumatoid arthritis was 20 with a sensitivity
of 90% and specificity of 80% and the serum cutoff value was 15 with a sensitivity of 93% and specificity of 53.3%.
Area under ROC curve for synovial ADA, ESR and CRP co-linearity was 99%. Conclusion: We concluded that synovial
total ADA assay can be a sensitive and specific test, being suitable for rapid diagnosis of rheumatoid effusions.