Performance of a urine dipstick test in detecting proteinuric dogs

Background: In clinical practice the detection of proteinuria in dogs relies on protein determination by urine dipstick tests. However, to confirm results and to quantify proteinuria, urine must be sent to external laboratories for protein:creatinine ratio (UPC) assessment. Objective: To assess the ability of Cliniteck Microalbumin 9 reagent strips (CM9; Siemens) to detect proteinuric dogs. Methods: Sixty-one samples were tested. In addition to proteins, CM9 provides semi-quantitative concentration of albumin (10, 30, 80, 150 mg/L), albumin to creatinine ratio (UAC; negative, 30–300, 4300 mg/g), and UPC (negative, 300, 1,500, 3,000, Z5,000 mg/g). UPC was determined also by quantitative reference method and 0.2 was used as the cutoff to identify proteinuric dogs. Ability to detect proteinuric dogs was evaluated for the following CM9 parameters: protein (protUSG); UPC; and UAC. Samples were interpreted as proteinuric when protein Z21or protein Z11and USG " 1.012 (Zatelli et al. 2010), UPCZ300 mg/g and UACZ30 mg/g. Results: protUSG, UPC, and UAC yielded respectively: accuracy 80.3%, 75.4%, and 85.2%; sensitivity 79.5%, 89.7%, and 94.9%; specificity 81.8%, 50%, and 68.2%; positive (and negative) predictive value 88.6% (69.2%), 76.1% (73.3%), and 84.1% (88.2%); and diagnostic odds ratio 15; 8.75, and 39.64. Agreement with reference UPC was 0.56 (protUSG), 0.427 (UPC), and 0.663 (UAC). Negative UAC result was reliable (correctly excluding proteinuria) when USG41.012. Positive UAC result was reliable (correctly identifying proteinuria) when UAC4300 or UAC= 30–300 with albumin = 150 and/or UPCZ1,500 and/or USGZ1,030. Conclusions: UAC provided the highest performances with exception of specificity (higher for protUSG). UAC results from Cliniteck Microalbumin 9 reagent strips can improve correct identification of proteinuric dogs in clinical practice. Exact quantitative determination of UPC is still mandatory in some cases of UACo30 and UAC= 30–300.