PROSPECTIVE-STUDY OF SERUM AND URINARY NITRATE LEVELS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective. To study prospectively whether serum and urinary nitrate le vels are related to lupus activity. Methods. Fifty patients with syste mic lupus erythematosus(SLE) were studied prospectively for 2 yr. Ever y 4 months, the SLE Disease Activity Index (SLEDAI) was administered t o the patients, and blood and 24 h urine samples were obtained; 88 hea lthy controls were also studied. Nitrate levels were measured by the G reiss method. Statistical analyses were performed using standard param etric and non-parametric tests, and analysis:of serial measurements. R esults. Twelve patients suffered infections, 12 active nephritis and 1 7 episodes of non-renal activity. By analysis of serial measurements, serum and urinary nitrate levels did not correlate with SLEDAI. C-Reac tive-protein (CRP) levels, presence of infection and creatinine cleara nce weakly influenced nitrate levels. Conclusions. In SLE, serum and u rinary nitrate levels do not parallel lupus activity. Other variables, related or not to SLE, seem to affect these levels.