THE ROLE OF URINARY BIOMARKERS IN THE PREDICTION OF TUBULOINTERSTITIAL KIDNEY INJURY IN CHILDREN FOLLOWING COVID-19

The COVID-19 pandemic has demonstrated the vulnerability of the kidneys as target organs due to high ACE2 expression in renal tubular epithelial cells. The aim of this study was to develop a diagnostic and prognostic approach for pediatric acute pyelonephritis based on the assessment of urinary biomarkers of kidney injury. A total of 100 children aged 7–17 years with acute pyelonephritis were included and divided into two groups according to previous COVID-19 history, along with 25 clinically healthy children as a control group. All participants underwent urinalysis, and measurement of urinary KIM-1, NGAL, β₂-microglobulin, and L-FABP levels. Children with a history of SARS-CoV-2 infection showed significantly elevated urinary biomarker levels and more pronounced subclinical signs of tubulointerstitial injury, including leukocyturia, microhematuria, proteinuria, as well as reduced titratable acidity and ammonia excretion (p<0.001). These findings indicate predominant tubulointerstitial kidney damage even in the absence of clinical manifestations. Early assessment of urinary biomarkers is essential for timely diagnosis and optimization of patient management.