Urinary sediment predicts active proliferative glomerular diseases

Background and Hypothesis Several studies have demonstrated the utility of urinary sediment (U-sed) examination in patients with glomerular diseases (GD). In this prospective study we have hypothesized that, with a standardized approach for U-sed preparation and examination, we could distinguish proliferative GD (PGD) from non-proliferative (NPGD) and predict GD with a high activity score at renal biopsy (RB). Methods The U-sed of 285 patients with 12 different biopsy-proven GD were investigated, 172 with PGD and 113 with NPGD. All RB were scored for the presence/absence of active and chronic histologic lesions. For each U-sed we evaluated the frequency and number of red blood cells (RBC), white blood cells (WBC), renal tubular epithelial cells (RTEC) and of 8 types of casts were. We also compared the frequency and number of RBC and WBC with the results supplied by the reagent strips (R-strip) for urine hemoglobin (U-Hb) and leukocyte esterase (U-LE). Results Patients with PGD had higher frequencies and numbers of RBC, WBC, RTEC and of casts containing RBC, WBC, and RTEC. PGD also had higher numbers of waxy casts while NPGD had higher numbers of fat casts. A good correlation was found between RBC and U-Hb, while U-LE, compared to WBC, supplied a high number of false negative results. In predicting PGD, U-sed RBC and WBC supplied the most significant area under the curve (AUC): 0.86 and 0.83 respectively; 0.88 when they were considered together vs 0.80 of the AUC with combined U-Hb and U-LE. An expert U-sed examination adding RTEC and RBC casts, reached an AUC of 0.90. U-sed alone was also superior to the combination of patient’s gender, age, serum creatinine and urine proteins (AUC=0.84). When added to all these variables, U-sed reached the AUC of 0.96. Conclusion U-sed is a useful tool to predict the presence of PGD with a high activity histological score.