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Analytic and diagnostic differences in measurement of urinary proteins using pyrogallol red or blue comassie

Rossi, G.ORCID: 0000-0003-4879-9504, Bertazzolo, W., Vitiello, T. and Paltrinieri, S. (2014) Analytic and diagnostic differences in measurement of urinary proteins using pyrogallol red or blue comassie. Veterinary Clinical Pathology, 44 (1). E23.

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The purpose of the study was to compare pyrogallol red (PR) and blue Coomassie (BC) for quantification of proteinuria in dogs, and to assess whether these methods affect patient’s classification as proteinuric or not. The concentration of urinary protein (UP) was determined using PR and BC on 337 urine samples. Urinary creatinine (UC) was also measured and the urinary protein to creatinine ratio (UPC) was calculated. The UP and the UPC obtained with PR and BC were compared to each other using a Wilcoxon signed rank test and method agreement using Passing-Bablok and Bland-Altman tests. The concordance of methods in classifying samples as non proteinuric (NP, UPC<0.2) borderline proteinuric (BP, UPC 0.2–0.5) or proteinuric (P, UPC >0.5) was assessed using the Cohen’s kappa test. PU and UPC were significantly higher (P < 0.001) with BC than with PR. Constant and proportional errors were found for both UP (intercept 7.1, 95% confidence interval [CI] = 5.9–8.2, slope: 1.3, 95% CI = 1.3–1.5) and UPC (0.1, 95% CI = 0.1–0.1, and 1.4, 95% CI = 1.3–1.6). The concordance in classifying samples as NP, BP or P was low (k = 0.54). The k coefficient increased (0.81) if BP samples were included in the NP group. BC overestimates the UP compared with PR. This overestimation increases at high UP values. The use of BC instead of PR affects the classification of samples as P, BP or NP. However, the higher k value obtained when BP samples are included in the NP group suggests that concordance in identifying samples with frank proteinuria (UPC >0.5) is acceptable.

Item Type: Journal Article
Publisher: American Society for Veterinary Clinical Pathology
Copyright: © 2015 American Society for Veterinary Clinical Pathology
Other Information: Poster presentation given @ European Society of Veterinary Clinical Pathology (ESVCP)/ European College of Veterinary Clinical Pathology (ECVCP) 16th Annual Congress. Milan, Italy. October 1 - 4 2014
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