Validity of leukocyte estrase test for detection of pyuria in patients with urinary tract infection

Abstract

Objective: To determine the sensitivity and specificity of LET for detection of significant pyuria in patients with UTI, keeping microscopic examination of urine as gold standard.

Study Design: Cross-sectional (validation) study.

Materials and Methods: 124 patients between 20-70 years of age with dysuria, urgency, increased urinary frequency, gross pyuria, flank pain, suprapubic pain, or clinical suspicion of UTI . Urine was collected in all patients by the midstream clean-catch technique. The urine sample was divided into two containers. LET was done on spot within five minutes. The second container was sent to laboratory for microscopic examination.

Results: Our study results showed that sensitivity, specificity, PPV and NPV were found to be 60.5%, 60%, 92.9, 15.0% in male group; 68.7%, 44.4%, 90.2%, 16.0% in female group; and 65.5%, 50.0%, 91.1%, and 15.6% in overall study population respectively.

Conclusion: LET has a high PPV (>90%) and can be used as a diagnostic test in high prevalent areas, where it may serve as a useful tool for spot diagnosis of UTI. It is not much useful as a diagnostic test in areas where the prevalence of disease is low.

Key words: UTI, Leukocyte Esterase, Dipstick, Urine analysis, Pyuria, Bacteriuria, Sensitivity, Specificity, Positive Predictive Value, Negative Predictive Value.