Urinary sediments could differentiate endocapillary proliferative lupus nephritis and endocapillary proliferative IgA nephropathy

This study investigated the differences in urinary sediment findings between patients with endocapillary proliferative lupus nephritis (LN) and patients with endocapillary proliferative IgA nephropathy (IgAN) and further evaluated the associations of leukocyturia with disease activity, pathological features and prognosis. The urinary sediments of 126 patients, including 92 with LN and 34 with IgAN, with renal-biopsy-proven endocapillary proliferative glomerulonephritis (EPGN) were examined by a standardized method. The urinary elements investigated included various cells, casts and crystals. The associations of leukocyturia with disease activity, pathological features and prognosis were further analyzed. In the patients with EPGN, normal to mild leukocyturia (≤12/HPF) and moderate to severe leukocyturia (>12/HPF) were found in 52 (41.27%) and 74 (58.73%) patients, respectively. The proportion of moderate to severe leukocyturia and the frequencies of urinary white blood cell casts and waxy casts were significantly higher in endocapillary proliferative LN than those in endocapillary proliferative IgAN (P < 0.001, P = 0.020, P = 0.010, respectively). In the endocapillary proliferative LN group, the levels of leukocyturia were significantly correlated with serum creatinine (r = 0.288, P = 0.005), eGFR (r = −0.284, P = 0.006), serum C3 (r = −0.275, P = 0.009), SLEDAI scores (r = 0.383, P ≤ 0.001) and glomerular leukocyte infiltration (r = 0.285, P = 0.002). A multivariate analysis showed that leukocyturia was an independent risk factor for renal outcomes in endocapillary proliferative LN (HR: 1.456, 95% CI: 1.083-1.957, P = 0.013) but not in IgAN. Urinary sediments of LN with EPGN and IgAN with EPGN differed in many aspects. Leukocyturia could reflect the disease activity and prognosis of EPGN, especially in endocapillary proliferative LN.