The comparison of the urine RBC phase contrast microscopy and immuoperoxidase stain in differentiation of renal and nonrenal hematuria
ASN 30th Annual Meeting, San Antonio
J Am Soc Nephrol (Sep) 8:90A 1997
The distinction between renal and non-renal origin of RBCs is important in setting the initial direction of the workup of hematuria. Dysmorphic RBCs by phase microscopy has been the most commonly used indicator or renal origin. The authors compared that method with the more recent technique of demonstrating, by immunoperoxidase staining, tubular Tamm-Horsfall protein on the RBCs, hence their renal origin.
They used both methods in 26 patients with proven renal hematuria, and in 23 with proven non-renal hematuria. Results for IP were reported as % of RBC's with + staining, with range and median values reported as well. dysmorphic RBCs were reported similarly, as percentages and ranges. They calculated sensitivity and specificity for both methods and found IP to be better (57.7% and 100%, respectively, for IP, vs. 30.9% and 95.7%, respectively for phase contrast).
Comment: If the finding of IP as 100% specific (i.e. no non-renal case had 20% or more IP+ RBCs) is confirmed, it may be useful in avoiding costly urologic studies in selected patients, but it must be remembered that these RBC studies are not diagnostic in themselves, but simply point to the relative yield to be expected from nephrologic vs. urologic workups for definitive diagnoses. (James A. Sondheimer MD, Wayne State University, Detroit, MI)
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ASN 30th Annual Meeting, San Antonio
Proteinuria/Hematuria : Diagnostic approach to hematuria