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Meauring Urine Protein in Cats

Lyon SD, Sanderson MW, Vaden SL et al: Comparison of urine dipstick, sulfosalicylic acid, urine protein-to-creatinine ratio, and species-specific ELISA methods for detection of albumin in urine samples of cats and dogs, J Am Vet Med Assoc 236:874, 2010.

The development of persistent protein in urine with inactive urine sediment is an established marker for chronic kidney disease (CKD). There is evidence to suggest an association between renal proteinuria and the progression of CKD in dogs and cats. The more marked the proteinuria, the greater the risk for progression of renal disease. This study evaluated the use of dipstick, sulfosalicylic acid (SSA), and urine protein-to-creatinine ratio (UP:C) methods for use in detection of albumin in urine. 347 feline urine samples were analyzed by the prior three methods and compared with a species-specific ELISA to determine sensitivity, specificity, positive predictive value (PPV), negative predictive value, and positive and negative likelihood ratios. The data for cats revealed poor specificity and PPV (more false positives) for the dipstick and SSA methods.  The UP:C method had high specificity for albuminuria in cats but low sensitivity (more false negatives). The results of the study in cats showed that when both the urine dipstick and SSA test results were in the trace to 1+ range, the positive results are best confirmed with a more specific-specific ELISA assay. Detection of albumin in urine from cats should always be confirmed with this highest quality assay. The UP:C test resulted in an unacceptable level of false-negative results. This test should not be used as a routine screening test for albumin detection in urine of clinically normal cats, especially for those with low-level albuminuria. [VT]

Related articles:
Jepson RE, Brodbelt D, Vallance C et al: Evaluation of predictors of the development of azotemia in cats, J Vet Intern Med 23:806, 2009.