The value of urinalysis in presumptive diagnosis of urinary tract infection in children

Abstract

Background Definite diagnosis of urinary tract infection (UTI) should only be established based on culture of urine specimen, otherwise it would be considered presumptive. Since urinalysis provides more rapid information than urine culture, clinicians should consider to utilize urinalysis as a decision-making tool for initiating treatment of UTI. Objective To determine the sensitivity, specificity, predictive val- ues, and accuracy of several urinalysis parameters, namely the ni- trite, leukocyte esterase (LE), Gram staining, and methylene blue reductase (MBR) tests, in supporting the diagnosis of UTI. Methods This diagnostic test was done on 30 subjects with pyuria during the period of April to June 2004. The sensitivity, specific- ity, positive predictive value (PPV), negative predicitve value (NPV) as well as the accuracy were calculated for each urinalysis parameter with urine culture as the gold standard. The relation- ship between categorical variables was analyzed by Fisher's exact test or chi square test. Results The sensitivity, specificity, PPV, NPV and accuracy for nitrite test, leukocyte esterase (LE) test, Gram staining, and MBR test were respectively as follows: nitrite test showed 90.5%, 66. 7%, 86.4%, 75%, and 83.3%; LE test yielded 95.2%, 33.3%, 76.9%, 75%, and 76.4%; Gram staininglOO%, 44.4%, 80.8%, 100%, and 83.3%; and MBR test 85.7%, 100%, 100%, 75%, and 90%. Conclusions The MBR, among other urinalysis routine tests, has the highest specificity and accuracy as well as high sensitivity in establishing a presumptive diagnosis of UTI

Keywords

• presumptive diagnosis
• urinalysis
• UTI