The utility of combined urine dipstick analysis and specific gravity measurement to determine feline proteinuria

Abstract

Objectives: To assess the utility of urine dipstick strips for detection of feline proteinuria when used in combination with urine-specific gravity, compared with urine protein-to-creatinine ratio as the gold standard. Materials and Methods: Retrospective analysis of clinical records of comprehensive urine examination obtained from cats presented to a referral hospital. Diagnostic agreement and test accuracy were calculated for the dipstick test alone and in combination with the urine-specific gravity, using different cut-off values for proteinuria. Receiver-operating characteristic curves were also calculated. Results: A total of 121 urine samples were included. The diagnostic agreement between dipstick and urine protein-creatinine ratio was poor. A dipstick result of equal or greater than “Trace” (0.1–0.3 g/L) had a sensitivity of 81% and a specificity of 31% to detect proteinuria. Grouping the samples by urine-specific gravity did not increase dipstick agreement with the urine protein-creatinine ratio and only resulted in a slight improvement in the accuracy of detecting proteinuria. Clinical Significance: The dipstick test was not accurate for detecting proteinuria when combined with urine-specific gravity in cats. Clinicians should not rely on this test and, regardless of the urine concentration, other appropriate quantitative methods such as urine protein-creatinine ratio should always be performed to detect proteinuria in cats.