ABSTRACT
Purpose. To determine the clinical and laboratory features of the course of acute pyelonephritis in children with a history of COVID-19 and to determine the risk of developing chronic kidney disease. Material and methods. The main cohort consisted of 36 patients with the debut of acute pyelonephritis, who had previously suffered COVID-19, the average age was 7,5 years. The comparison group included 47 patients with the onset of acute pyelonephritis and a normal level of IgG antibodies to SARS-CoV-2, the average age was 7,0 years. Laboratory tests included full blood count and urinalysis, blood biochemistry, procalcitonin, urine microalbumin, urine creatinine, Zimnitsky urine test, bacteriological urine test, glomerular filtration rate, coagulogram, and Lipocalin-2 associated with neutrophil gelatinase (NGAL) in the urine. Results. Patients with a history of COVID-19, at the onset of acute pyelonephritis, demonstrated a higher incidence of apostematous pyelonephritis, a higher degree of damage to the tubulointerstitial kidney tissue, a high frequency and a higher level of hematuria, proteinuria, hyperfiltration, hypostenuria, as well as a more significant increase in fibrinogen, CRP, procalcitonin, and uNGAL/Cr levels than children of the comparison group. It was shown that almost half of the children with acute pyelonephritis who had had COVID-19 retained urinary syndrome during examination 3–4 months after the onset of the disease. Conclusion. Thus, long-term effects of the SARS-CoV-2 virus on the renal parenchyma were confirmed, even in asymptomatic children. The high level of uNGAL/Cr in children with acute pyelonephritis who had had COVID-19, which was almost 8 times higher than in the comparison group, reflects more pronounced damage to the tubulointerstitial kidney tissue. The risk of developing chronic kidney disease in this group was 3,5 times higher.