Urinary neopterin in idiopathic retinal vasculitis

AIMS—To determine whether urinary neopterin:creatinine (UNC) ratios relate to disease activity in idiopathic retinal vasculitis (RV). METHODS—18 patients with RV were prospectively recruited into a year long longitudinal study. Patients collected first morning urine samples on a weekly basis and on the same day completed a diary which documented their subjective view of RV activity and any concurrent infection. They were examined in clinic on a 6-8 weekly basis and an objective assessment was made of RV disease activity. 14 healthy controls collected urine samples in the same way. RESULTS—UNC ratios were significantly higher in patients than in controls (p=0.004, Mann-Whitney U test). UNC ratios were significantly higher when, according to their diaries, the patients had a subjective flare up of RV (p=0.001, Mann-Whitney U test). Subjective increased RV activity occurred more often when the patients had a concurrent infection (p<0.0001, χ2 test). There was no significant difference in the UNC ratio between objective clinical relapse and non-relapse of RV. There was moderate agreement between the clinical assessment and patients' subjective impression of RV activity (κ=0.48). CONCLUSIONS—Higher neopterin levels reflect cell mediated disease that occurs in RV, but UNC ratios are not recommended as a means of monitoring clinical disease activity in RV.