“…The results of this study were in agreement with that in the current study. In 2012, Ozkan et al 18 evaluated the usefulness of tryptophan degradation and neopterin levels in active rheumatoid arthritis patients under therapy. They found that neopterin levels correlated positively with kynurenine (r = 0.582, p < 0.02), kynurenine/tryptophan (r = 0.486, p < 0.05), erythrocyte sedimentation rate (r = 0.472, p < 0.05), and RF (r = 0.478, p < 0.05) in a group of rheumatoid arthritis patients, which are in concordance with the results of the present study.…”