Blood Analysis for Screening of Electrolyte and Kidney Function Alterations in Patients with Febrile Urinary Tract Infection

To describe the prevalence, severity, risk factors, and clinical relevance of electrolyte disturbances and acute kidney injury (AKI) during febrile urinary tract infection (fUTI). Retrospective observational study of well/fair-appearing patients between two months and 16 years, with no previous relevant medical history, diagnosed with fUTI in the pediatric emergency department(PED) with subsequent microbiological confirmation. Analytical alteration (AA) data were considered: AKI (creatinine elevation x1.5 the median for age), plasma sodium alteration (≤130 or ≥150mEq/l), potassium alteration (≤3 or ≥6mEq/l). We included 590 patients, 17.8% presented AA (13 hyponatremia, 7 hyperkalemia, and 87 AKI). No patient presented severe analytic alterations or a higher frequency of symptoms potentially attributable to these alterations (seizures, irritability, or lethargy). Risk factors associated with these AA were clinical dehydration (OR=3.5 CI95%:1.04-11.7; p=0.044) and presenting a temperature >39°C (OR=1.9 CI95%:1.14-3.1; p=0.013). Electrolyte and renal function disturbances are infrequent in the previously healthy pediatric population with a fUTI. If present, they are asymptomatic and not severe. Based on our results, performing systematic blood analysis to rule out AA appears no longer justified, especially in the absence of risk factors.