The Frequency of Lupus Nephritis and Hematuria in Patients with Systemic Lupus Erythematous in Isfahan City, Iran

Concerning the importance and the high frequency of renal involvement in patients with systemic lupus erythematosus (SLE), and the ability to measure the value of hematuria on predicting the incidence of lupus nephritis, this study aimed to determine the frequency of lupus nephritis in SLE patients with hematuria. This cross-sectional study investigated 500 patients with SLE in Isfahan City, Iran, between the years 2001 and 2015. Medical history, as well as demographic and clinical data of patients including the levels of C3, C4, and anti-dsDNA antibody, presence of lupus nephritis, proteinuria, cellular cast, pyuria, urinary tract infection, urinary tract stones, congenital renal defects, and history of any kidney disease were obtained from the patients' files at the end of the study period, and analyzed using SPSS software. The frequency of hematuria in patients with lupus nephritis was 36.1%, and there was no significant relationship between the presence of hematuria and the existence of lupus nephritis in patients with SLE [odds ratio (OR) = 0.727, confidence interval of 95% = 0.376-1.648, P = 0.520]. The individuals with lupus nephritis had a lower age distribution compared to the cases without it (P = 0.005). Most of the cases in the lupus nephritis group had low C3 and C4, but most patients in non-lupus nephritis group had normal levels of C3 and C4 (P < 0.05).  The relative frequency of lupus nephritis in SLE patients with hematuria was approximately 36%. Therefore, the presence of hematuria in patients with SLE may account for incidence of lupus nephritis one-third of the cases.