A preliminary evaluation of the interaction between urine specific gravity and leukocyte esterase results using Bayer Multistix® and the Clinitek® 500

Abstract

Objectives To determine the sensitivity of the leukocyte esterase (LE) pad to predict microscopically quantified white blood cells in urine sediment and to assess the interaction of urine specific gravity (SG) on leukocyte esterase sensitivity. Methods Microscopic quantification of white blood cells in urine sediment was performed manually and automated chemical urinalysis was performed using the Bayer Clinitek® 500 and Multistix® 8 SG strips on 422 random urine specimens. Results The sensitivity of the leukocyte esterase pad to predict white blood cells in centrifuged urine was 58% (61/106). There was a weak but statistically significant negative correlation between SG and LE pad performance, r = −0.12, p < 0.05. Conclusions The 58% sensitivity of the Multistix® leukocyte esterase detection of white blood cells in urine sediment was consistent with previous reports. The negative correlation of specific gravity and leukocyte esterase provides partial explanation for the lack of sensitivity of the leukocyte esterase test.