Download evaluation of proteinuria in cats: comparison between coomassie

EVALUATION OF PROTEINURIA IN CATS: COMPARISON
BETWEEN COOMASSIE BLUE AND PYROGALLOL REDMOLYBDATE
M. Giraldia, S. Patrinieria, G. Rossia, W. Bertazzolob, P. Scarpaa
1
Department of Veterinary Sciences and Public Health, University of Milan, Via Celoria
10, Milano 20133, Italy;2Veterinary Animal Hospital Città di Pavia, Pavia, Italy
Pyrogallol Red-Molybdate (PRM) and CoomassieBlu (CB) are the commonest
assays used for evaluation of urinary protein (UP) concentration. Data about
method-dependent differences are lacking. Therefore, the aims of this study
were to compare UPs and urinary protein:creatinine (UPC) ratios recorded with
PRM and CB and to evaluate intra-assay coefficients of variations (CV).
Urine
samples
were
collected
from
58
client-owned
cats
by
ultrasonographically-guided cystocentesis irrespective of results of sediment or
of underlining diseases. UPs were measured with PRM and CB in triplicate. The
mean values were used to calculate UPC ratios. The Wilcoxon signed rank test
was performed to investigate the differences between UP obtained with PRR
and CB and between calculated UPC ratios. Correlation between methods was
assessed with the Spearman test and agreement with Passing-Bablok and
Bland-Altman tests.CV were calculated in 15 samples by 20 repeated
measurements of UPs (with both methods). Concordance between UPC ratios of
both methods in classifying patients as proteinuric, borderline proteinuric or
non proteinuric(according to IRIS sub-staging) was assessed using Cohen’s k
coefficient test.
Proteinuria and UPC ratio showed statistically differences between methods
(p<0,0001) with CB method having higher values. Agreement between
methods showed constant and proportional errors. The two methods were
correlated for both UP and UPC (p<0,0001).All intra-assay CVs were <10%.
Concordance in classifying samples was moderate (k=0,476).
CB method was precise at any level of proteinuria but the higher UPC obtained
with CB compared to PRM may affect interpretation and clinical decisions
according to the IRIS guidelines.