Is the Red Cell Morphology Really Useful to Detect the Source of Hematuria?

Abstract

Morphological analysis of urinary red blood cells by phase-contrast microscopy to identify the source of bleeding was, and still is, widely used also as a starting point for workup. To evaluate the reliability of this approach, we studied 129 outpatients presenting with persistent isolated microhematuria; 31 subjects also had mild proteinuria (1 g/day), while 21 had pathological albumin levels. All patients were followed for a period of 6 years. During this time, 6 patients underwent renal biopsy for the onset of macrohematuria episodes and proteinuria of 2-3 g/day. Glomerular bleeding was identified in only 14.7% of the patients, despite the persistent microhematuria and the presence of proteinuria or microalbuminuria. The renal origin of the urinary erythrocytes correlated with histological findings in only 2 of 6 patients with dysmorphic erythrocytes who developed proteinuria (exceeding 1 g/day), and none with isomorphic erythrocytes showed urological abnormalities. These results challenge the validity and reliability of morphological analysis to identify the source of bleeding along the urinary tract.

Dysmorphic erythrocytes and G1 cells as markers of glomerular hematuria

“…Our specificities for different cut-off levels of G1 cells agree well with those of others [22,23,24]. However, since 36% of the urine samples from our patients with biopsy-proven glomerulonephritis contained no G1 cells, our diagnostic sensitivities for percentage G1 cells were lower than those reported by Kohler et al [3], Lettgen and Wohlmuth [8], and Tomita et al [4] for the corresponding cut-off levels.…”

“…However, the clinical usefulness of this technique remains controversial, since there is no agreement over the criteria for the interpretation of the urinary dysmorphic erythrocytes [3,4] or the minimum number of dysmorphic erythrocytes deemed to indicate glomerular hematuria. The diagnostic cut-off for the percentage of dysmorphic erythrocytes giving a definitive diagnosis of glomerular hematuria has varied between 10% and 80% [5,6,7,8,9,10,11,22,23,24]. In these studies the sensitivities have ranged from 21% to 95% and the specificities from 75% to 100%.…”

Usefulness of Urinary Erythrocyte Morphology for the Determination of the Source of Hematuria

“…by Favaro et al [1]. In this article, the authors assumed that urinary erythrocyte morphology is not a reliable method to determine the source of hematuria as they observed no correspondence between their findings and the underlying pathology.…”

“…However, we must keep in mind that hematuria of IgA nephropathy may be nonglomerular and glomerular as well [5]. In fact, Favaro et al [1] failed by proposing that erythrocyte morphology did not help to point out the origin of hematuria when they accepted the cause of hematuria was renal. It has been reported that vascular lesions may be present in the lower urinary tract causing concomitant glomerular and nonglomerular hematuria in patients with IgA nephropathy [6].…”

Urinary Microscopy as Seen by Nephrologists

“…As demonstrated by several in-vestigators (10 -15), we too rely upon the analysis of erythrocyte morphology to determine whether the bleeding is glomerular or non-glomerular ( Fig. We find this method useful to address the early work-up of patients with isolated microscopic haematuria (9), even though in some cases the evaluation may be difficult and bears the risk of subjectivity (16), and in spite of the fact that some investigators have found this approach of questionable value (17). We find this method useful to address the early work-up of patients with isolated microscopic haematuria (9), even though in some cases the evaluation may be difficult and bears the risk of subjectivity (16), and in spite of the fact that some investigators have found this approach of questionable value (17).…”