Clinical predictive value of the urine leukocyte esterase test positivity in childhood.

Background: False negative or positive results may occur in the urine dipstick test for leukocyte esterase (LE), which is used to determine urinary tract infection (UTI). We aimed to investigate the clinical importance of the presence or absence of pyuria in urine sediment for diagnosing UTI in the presence of positive LE in dipstick analysis.

Methods: Patients admitted to the pediatric nephrology outpatient clinic with positive urine LE tests were divided into two groups: those without pyuria (Group 1) and those with pyuria (Group 2) in their urine sediment. Hospital files of the patients were evaluated retrospectively for demographic variables, lower or upper UTI symptoms, physical examination for phimosis and vulvovaginitis, urinalysis for LE and nitrite tests, urine sediment microscopy, urine culture, complete blood count and C-reactive protein. Both groups were compared for the significant growth of pathogenic bacteria in urine cultures along with clinical and laboratory parameters.

Results: Among 578 children giving samples for urinalysis, there were 287 cases with positive LE tests. Groups 1 and 2 included 123 and 164 cases, respectively. The proportion of girls was higher in Group 1 and vulvovaginitis rate was higher among the girls in Group 1. Girls with vulvovaginitis were mostly prepubertal. Upper UTI symptoms, significant pathogen growth rate, and elevated acute phase response were more common in Group 2. In addition, the phimosis rate was more common among the boys in Group 1 with false positive LE test.

Conclusions: Children with positive LE tests without pyuria are mostly prepubertal girls and there is a high rate of vulvovaginitis in these girls. Unnecessary tests and treatments for UTI may be avoided with detailed history and physical examination in prepubertal girls who have a false positive LE test. We also found, for the first time, that a false positive LE test is significantly associated with phimosis in boys.