Evaluation of Kidney Functioning in Children with Renal Complications During COVID-19 Pandemic: A Retrospective Observational Cohort Clinical Study
Authors: Axmedjanova N. I. , Axmedjanov I. A. , Ismoilova Z. A. , Gapparova G. N. 
Published: June 2023

Background. An increase in a quantity of children with acute renal insufficiency associated with infectious diseases, including COVID-19 is a growing problem in nephrology. Such insufficiency is often expressed in pyelonephritis. Due to a lack of specific signs or obvious clinical symptoms and their correct interpretation, acute renal insufficiency against the background of COVID-19 is first identified in the period of steady worsening of the kidney functioning. An accurate non-invasive diagnostic test is yet to be fully developed, therefore, determination of the mechanisms of complications is considered to be challenging and can contribute to the formation of irreversible renal injury.

Objective — to determine and evaluate characteristics of the renal status in children with acute pyelonephritis against the background of COVID-19.

Methods. A retrospective observational cohort clinical study of 65 children with acute pyelonephritis was carried out. The study also included a control group of 20 healthy children, who were observed during routine health checkup. The patients were observed at the Nephrology Unit, Samarkand Regional Pediatric Multidisciplinary Medical Center, Uzbekistan. Laboratory examination was carried out on the basis of Clinical Diagnostic Laboratory, Samarkand Regional Pediatric Multidisciplinary Medical Center, Uzbekistan, and Laboratory of Innova Clinic, Uzbekistan. The study was conducted from January 2021 to December 2022 and involved participants with the history of COVID-19 before treatment. Thus, two cohorts were formed: group 1 comprised 30 children with acute pyelonephritis and without a history of COVID-19; group 2 consisted of 35 patients with acute pyelonephritis against the background of COVID-19. In order to evaluate the renal status, examination of the glomeruli, proximal and distal tubules was carried out. The study included investigation of “urinary syndrome” indicators — leukocyturia of neutrophil origin, microhematuria, proteinuria, and bacteriuria. The obtained laboratory data were analyzed using variance and given in SI System — the International System of Units. The calculations were carried out using StatPlus 7 (AnalystSoft Inc., USA).

Results. Renal function is decreased in an acute period due to reduced functionality of concentration and distal tubule, which were more significantly affected in group 2. Inflammatory changes in the renal tissue due to the toxic effects of coronavirus infection underlie the abnormalities detected. The history of COVID-19 is reckoned from the date of admission and ranges from 3 weeks to 2 months. Renal insufficiency in children with COVID-19 history is manifested irrespective of their clinical polymorphism, due to impairment of its tubular structures (reabsorption, acidogenesis and ammoniogenesis, osmotic concentration) and glomerular filtration. A statistically significant reduction in acidogenesis (p = 0.001) was recorded in patients with acute COVID-associated pyelonephritis.

Conclusion. Children with COVID-19 respiratory symptoms require monitoring their renal functions for early diagnosis and treatment. Long-term monitoring of patients with isolated urinary syndrome in the acute period is needed to detect the underlying renal disease.