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

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.