Effects of urinary tract inflammation and sample blood contamination on urine albumin and total protein concentrations in canine urine samples.
BACKGROUND
Urinary tract inflammation and hemorrhage are believed to be common causes of proteinuria in dogs based on results of studies that measured total urine protein concentration. A method to quantify urine albumin (UAlb) concentration in dogs recently has become available; however, the effect of inflammation on albuminuria is unknown.


OBJECTIVE
The goals of this study were to determine the effects of urinary tract inflammation, as indicated by pyuria and sample blood contamination, on UAlb concentration and on urine protein:creatinine (UPC) ratio in dogs.


METHODS
Urine samples were obtained from dogs with pyuria that were presented to a veterinary teaching hospital or were part of a laboratory colony. To mimic the effects of hematuria, canine whole blood was added to a microscopically normal canine urine sample that had baseline albumin and total protein concentrations below the limits of detection. UAlb concentration was measured using a canine albumin-specific competitive ELISA. UPC ratio was determined using routine methods.


RESULTS
Of 70 samples with pyuria, 67% had negligible UAlb concentrations and 81% had normal UPC ratios. UAlb concentration but not UPC ratio was significantly higher (P < 0.05) in samples with concurrent hematuria or bacteriuria. When whole blood was added to normal urine, UAlb concentration did not exceed 1 mg/dL until the sample became visibly pink; the UPC did not exceed 0.4 at any dilution.


CONCLUSIONS
Many dogs with pyuria do not have albuminuria or proteinuria; however, albuminuria may be more likely in dogs with pyuria and concurrent hematuria or bacteriuria. Hematuria may not cause an increase in UAlb concentration until it becomes macroscopic and even then may not increase the UPC ratio.
Vaden
Shelly L
SL
College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA. shelly_vaden@ncsu.edu
Pressler
Barrak M
BM
Lappin
Michael R
MR
Jensen
Wayne A
WA
D000419:Albuminuria / Q000209:etiology / Q000652:urine / Q000662:veterinary*; D000818:Animals; D003404:Creatinine / Q000652:urine; D004283:Dog Diseases / Q000175:diagnosis / Q000209:etiology / Q000652:urine*; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary; D005260:Female; D006417:Hematuria / Q000662:veterinary; D008297:Male; D009994:Osmolar Concentration; D011507:Proteinuria / Q000209:etiology / Q000652:urine / Q000662:veterinary; D011776:Pyuria / Q000150:complications / Q000175:diagnosis / Q000662:veterinary; D012680:Sensitivity and Specificity; D016482:Urinalysis / Q000379:methods / Q000662:veterinary; D014552:Urinary Tract Infections / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*
D003404:Creatinine