Differentiation of glomerular from non-glomerular hematuria by three different methods of microscopic examinations of erythrocytes in urine

Abstract

Background: Morphological examinations of urinary erythrocytes can be of diagnostic value in initial evaluation of hematuria. Dysmorphic urinary red blood cells are known to indicate a glomerular origin of bleeding. We examined the clinical usefulness of this test in a population complained of hematuria by use of three different methods: light microscopy, phase contrast microscopy, and Wright staining and compared their sensitivity and specificity. Methods: The study included 169 patients with hematuria (89 glomerular and 80 non-glomerular). The urine specimens were collected before invasive procedures such as biopsy and cystoscopy. In each urine sample, 100 urinary erythrocytes were examined. Statistical analysis was performed using Student's t test, correlation coefficient, and x2. Reliability parameters including sensitivity, specificity and predictive values of negative and positive tests were also evaluated. Results: Dysmorphic red cells were recorded as acanthocytes, doughnut-like cells, yeast like cells with more than one blebs and ghost forms. Isomorphic erythrocytes had uniform size and shape. Significant difference was found in the number of urinary dysmorphic red cells between the two groups of patients. Statistical analysis showed that by using percentage of glomerular type erythrocytes and setting the cut-off at 20-25%, the specificity for three procedures was almost the same (? 97.5%). But sensitivity for light microscopy, phase contrast microscopy, and Wright staining was in different ranges as 70.7%, 89.8%, and 86.5% respectively. Conclusion: It was concluded that with some limitations, these simple, non-invasive techniques were useful in identifying the source of bleeding in the work up of hematuria by considering that sensitivity of the methods were in the order of phase contrast microscopy, Wright staining, and light microscopy.