Urinary neopterin reflects clinical activity in patients with rheumatoid arthritis.

Neopterin is a marker for activation of cellular immunity. Urinary neopterin levels were measured in 106 patients with rheumatoid arthritis (RA) and in 45 patients with osteoarthritis. Levels were significantly higher in RA patients than in osteoarthritis patients and were strongly dependent on stage and activity of RA. Correlations with other laboratory parameters were weak. Multivariate analysis demonstrated that urinary neopterin levels reflected clinical activity better than did other laboratory findings. Thus, urinary neopterin determination might be useful in monitoring RA patients.