Urine neopterin: a new parameter for monitoring disease activity in patients with systemic lupus erythematosus

ABSTRACT

Urine neopterin/creatinine [N/C] ratio was determined in early morning samples of 16 children with active systemic lupus erythematosus [SLE] and 10 children with inactive SLE disease, using radioimmunoassay [RIA] for measuring urine neopterin Concentration. Compared with apparently healthy 20 control children the mean urine N/C ratio was significantly increased in patients with active [P <0.001] and inactive [P <0.01] SLE. The mean urine N/C ratio was also significantly higher in children with active than in. those with inactive SLE [P <0.001]. The urine N/C ratio did not distinguish between patients with renal activity and those with other types of clinical activity and it was not influenced by different drug regimens. The correlation between urine N/C ratio and erythrocyte sedimentation rate [ESR] was a positive linear one while there was no significant correlation between urine N/C ratio and serum C4. When testing urine N/C ratio at a cut-off value of >/= 300 micro mol neopterin/mol creatinine and ESR at a cut-off value of >/= 50 mm/hr and serum C4 at a cut-off value of patients