Urinary sediment predicts active proliferative glomerular diseases

Several studies have demonstrated the utility of urinary sediment (U-sed) examination in patients with glomerular diseases (GDs).In this prospective study we hypothesized that with a standardized approach for U-sed preparation and examination, we could distinguish proliferative GD (PGD) from non-proliferative GD (NPGD) and predict GD with a high activity score at renal biopsy (RB).

The U-sed of 285 patients with 12 different biopsy-proven GDs were investigated, 172 with PGD and 113 with NPGD. All RBs 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 (RBCs), white blood cells (WBCs), renal tubular epithelial cells (RTECs) and 8 types of casts. We also compared the frequency and number of RBCs and WBCs with the results supplied by the reagent strips (R-strip) for urine haemoglobin (U-Hb) and leukocyte esterase (U-LE).

Patients with PGD had higher frequencies and numbers of RBCs, WBCs, RTECs and of casts containing RBCs, WBCs and RTECs. PGD also had higher numbers of waxy casts while NPGD had higher numbers of fat casts. A good correlation was found between RBCs and U-Hb, while U-LE, compared with WBCs, supplied a high number of false negative results. In predicting PGD, U-sed RBCs and WBCs supplied the most significant area under the curve (AUC): 0.86 and 0.83, respectively; 0.88 when they were considered together versus 0.80 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 an AUC of 0.96.

U-sed is a useful tool to predict the presence of PGD with a high histological activity score.