Clinical evaluation of a leukocyte esterase test-strip for detection of feline pyuria.
Commercial macroscopic test-strips (dipsticks) that indirectly detect urine leukocytes by quantifying leukocyte esterase (LE) activity have been advocated as a simple, rapid, and inexpensive alternative to microscopic examination for detection of significant pyuria in urine specimens. The purpose of this study was to evaluate the diagnostic performance of a commercial LE test-strip for detection of feline pyuria. Two hundred and thirteen consecutive urine specimens were collected from 188 different feline patients and analyzed for LE activity with a LE test-strip (Multistix 2 Reagent Strips:Ames Division, Bayer Corp., Elkhart, IN). Results of the LE test-strip were compared with those of standard urine biochemical and microscopic sediment evaluations. Compared with urine sediment leukocyte counts, the LE test-strip had a sensitivity of 77%, a specificity of 34%, positive and negative predictive values of 14 and 91 % respectively, and an overall test efficiency of 39%. Multivariable logistic regression analysis did not reveal significant associations between pyuria (>5 WBC/hpf) and a positive LE test- strip reaction; however, hematuria, lipiduria, increasing age, and decreasing urine specific gravity were associated with a significantly increased risk for positive LE test-strip reactions. We conclude that the LE test-strip evaluated in this study is highly nonspecific for detection of significant pyuria in feline urine specimens and should not replace routine microscopic urine sediment examination in this species.
Holan
Kathleen M.
KM
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.
Kruger
John M.
JM
Gibbons
SSuzanne N.
SN
Swenson
Cheryl L.
CL