Role of urinary dysmorphic red blood cells in glomerular disease

Abstract

Introduction: The analysis of urine sediment is a tool that has been used for many years in clinical practice to evaluate kidney diseases. Detecting dysmorphic red blood cells (RBC’s) in urine is useful for the diagnosis of glomerular diseases. Objectives: To divide the cases of glomerular hematuria into two groups, depending on the presence or absence of acanthocytes, and to compare this factor with the histological findings of renal biopsies. Methods: In this observational, retrospective, analytical study, urine sediments of 276 patients were included. Two groups of subjects with glomerular hematuria were analyzed: D1 (presence of acanthocytes) and D2 (absence of acanthocytes). The results were compared with the renal biopsy histological findings, i.e. proliferative glomerulonephritis and non-proliferative glomerulonephritis, considered separately. The formed elements of the urine (red blood cell, white blood cell, waxy, granular and fatty casts), plasma creatinine concentration and 24-hour urinary protein were tested in the two groups. A logistic regression analysis was later performed to assess the independent variables among urine sediment findings, with the corresponding odds ratio (OR) and confidence intervals (CI 95%). Results: The samples were collected from 172 women (62.3 %) and 104 men (37.7 %). The presence of acanthocytes (D1) was 17 times more frequent in proliferative glomerulonephritis (PGN) than in non-proliferative glomerulonephritis (NPGN) [OR 17.7, CI 95% (9.6-32.5), p 0.001]. The presence of red blood cell casts was 8 times more frequent in PGN [OR 8, CI 95% (3.1-20.9)]. Cases of hematuria with no acanthocytes (D2) were 5 times more frequent in NPGN [OR 5.2, CI (2.4-11.3), p 0.001]. Fatty casts appeared more frequently in patients with NPGN, whereas white blood cell casts were more common in PGN cases. Conclusions: Renal histological findings revealed a significant correlation between glomerular hematuria without acanthocytes (D2) and nonproliferative glomerulonephritis (NPGN), while the presence of acanthocytes and red blood cell casts was associated with proliferative glomerulonephritis (PGN). The existence of acanthocytes in urine constitutes a useful tool to make a clinical distinction between these two conditions, but it does not replace renal biopsy to establish an accurate diagnosis and prognosis.