Urinary Tract Infection in Children: Diagnostic and Prognostic Utility of Biomarkers

In the diagnostic evaluation of urinary tract infection (UTI) in children, dipstick urinalysis and urine microscopy/culture are the initial steps. Although these investigations are not without their drawbacks, urine culture remains the gold standard. Biomarkers may also be used as diagnostic tools, predictors of complications, and renal parenchymal injury. This paper aims to review the studies reporting the utility of biomarkers in the diagnosis and prognostication of UTI. Using the key words- ‘urinary tract infection’, ‘children’, and ‘biomarkers’- the PubMed database was searched for systematic reviews/meta-analyses and original studies, which were published within the past 25 years. Information was also gathered from relevant textbooks published within the same period. Serum procalcitonin, urine/serum interleukin 6 (IL-6) and 8 (IL-8), as well as urine neutrophil gelatinase-associated lipocalin (NGAL) are the major biomarkers of febrile UTI. In addition, procalcitonin and these cytokines are reported to be early predictors of vesico-ureteric reflux (VUR) and renal parenchymal injury, while procalcitonin and IL-6 can also help to differentiate between lower UTI and upper UTI (pyelonephritis). Despite the wide range in the sensitivity and specificity of these biomarkers reported in the reviewed studies, the values are still acceptable. Some of these biomarkers may, in the future, obviate the need for invasive radiological tests, although their utility still require validation by further research. However, given the ability of imaging studies to detect structural abnormalities of the urinary tract, their use still remains relevant in the investigation of UTI despite the radiation risks associated with majority of them.