Localizing the site of hematuria by immunocytochemical staining of erythrocytes in urine.

We have further explored the immunocytochemical staining method to discriminate renal and nonrenal hematuria, reported by Abrass and Laird (Am J Kidney Dis 1987;9: 44-50). After fixation on slides with acetone, erythrocytes in urine were stained with antiserum against human Tamm-Horsfall protein. Reactions were made visible by using either a fluorescent second antibody or a biotinylated second antibody, avidin, and biotinylated horseradish peroxidase, producing an insoluble reaction product. The staining methods were validated with material from clinically diagnosed cases of hematuria of renal or nonrenal origin. In material from kidney transplantation patients, in samples from the catheter that were presumed to contain renal erythrocytes, 84.7% and 80.1% of the erythrocytes stained by the immunofluorescence and immunoperoxidase methods, respectively, whereas in samples from the catheter that were supposed to contain nonrenal erythrocytes, 9.3% and 13.1% of the cells stained. In a group of nontransplantation patients with various causes of renal hematuria, 87.3% and 89.8% of the erythrocytes in urine stained with the immunofluorescence and immunoperoxidase methods, respectively, whereas in samples from patients with hematuria of known nonrenal origin, 12.9% and 12.4% of the cells stained. Staining of erythrocytes in renal and nonrenal hematuria was significantly different (P less than 0.001) and better discriminated between renal and nonrenal hematuria than did inspection of the morphology of erythrocytes in urine.