Association between hyponatremia and disease severity in pediatric urinary tract infections

BackgroundAcute urinary tract infection (UTI) is a common disease in pediatrics, with around 8% of girls and 2% of boys experiencing a UTI by age 7y/o. UTIs can range from asymptomatic bacteriuria to acute pyelonephritis (APN) in severe cases involving renal parenchymal infection. UTI patients admitted to the pediatric ward usually have more severe clinical presentation, compared to those treated in the outpatient settings. Therefore, it will be helpful to have markers that predict the severity of the disease and the likelihood of having APN.MethodsWe performed a retrospective review on all pediatric UTI/APN patients treated in the inpatient setting at a Medical Center from October 2012 to September 2022. Patients were assigned to the "hyponatremia" or "eunatremia" group according to their serum sodium concentrations. Detailed information, including renal echo, blood, and urine test results, were collected for the analysis of multivariable logistic regression model.ResultsThe study included 344 patients, of which 99 (28.8%) had hyponatremia, and 245 (71.2%) had normal serum sodium levels. The hyponatremia group had higher APN frequency, renal echo abnormality, and higher CRP level. In multivariable analysis, hyponatremia was independently associated with increased serum glucose (OR: 1.01, 95% CI: 1.00-1.03, p = 0.0365) and CRP levels (OR: 1.00, 95% CI: 1.00-1.01, p = 0.0417), without a significant increase in APN frequency as the final diagnosis.ConclusionsOur findings suggest that hyponatremia in pediatric UTI patients may indicate a more severe disease, such as APNs, higher CRP levels, or renal echo abnormalities. The complex mechanisms underlying hyponatremia and its predictive value for disease severity warrant further investigation.