American Society for Veterinary Clinical Pathology (ASVCP) 47th Annual Meeting

The interpretation of the urinary protein to creatinine ratio(UPC) in urine samples with concurrent hematuria can be confusing, as blood may increase the protein level measured in the urine. To mimic hematuria, blood from 18 dogs was added to their own urine sample in increasing levels (from 0 to 5%) to determine whether the urine color for varying degrees of blood contamination can be utilized to aid interpretation of the validity of the UPC results. For each urine sample, urinary protein and creatinine were measured biochemically, urine dipstick analysis, specific gravity by refractometry and microscopic sediment examination were performed, and the urine color was visually assessed. A complete blood count (CBC) and serum biochemistry panel were performed on each dog. Blood contamination of the urine that did not result in a visible change in color of the urine sample from yellow (i.e., microscopic hematuria) did not increase the UPC above the normal range of <0.5. As such, in the presence of microscopic hematuria, the UPC level in yellow urine (with no evidence of concurrent urinary tract inflammation) should be considered valid. Thus, the practice of discouraging UPC assessment in animals with microscopic hematuria should be discontinued. However, hematuria that results in a visible color change from yellow may increase the UPC above 0.5. In this situation hematuria would need to be considered as a differential diagnosis for the proteinuria