Is the red cell morphology really useful to detect the source of hematuria?
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.
Favaro
S
S
Institute of Internal Medicine, Division of Nephrology, University of Padua, Italy.
Bonfante
L
L
D'Angelo
A
A
Giacomini
A
A
Normanno
M
M
Caló
L
L
Bordin
V
V
Vianello
D
D
Meani
A
A
Antonello
A
A
Borsatti
A
A
D000328:Adult; D004912:Erythrocytes / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006417:Hematuria / Q000209:etiology* / Q000473:pathology; D006801:Humans; D007668:Kidney / Q000473:pathology; D007678:Kidney Glomerulus / Q000473:pathology; D008297:Male; D008858:Microscopy, Phase-Contrast; D013997:Time Factors