The study’s objective was to comprehensively assess kidney function alterations in patients with COVID-19. The study was carried out in Moscow (Russia) in 2021. 100 patients of 19-30 years old (51 females and 49 males) took part in the survey. The study collected participant data on basal urine, serum creatinine, and estimated glomerular filtration rate from medical histories before COVID-19 infection. COVID-19 diagnosis (delta strain) was confirmed by polymerase chain reaction test. Serum creatinine was measured, considering age and race. Micro-albuminuria levels from daily urine samples were established. Laboratory blood tests included quantitative indices of blood-forming elements, hemoglobin levels, and biochemical parameters. Based on the results, the study observed a slight increase in serum creatinine levels after COVID-19 infection, with concentrations of 78.4±6.4 mmol/L before infection and 87.5±7.7 mmol/L after the disease (p≥0.05). The microalbuminuria-creatinine ratio also showed an increase. The glomerular filtration rate in renal glomeruli declined from 93.3±10.1 mL/min/1.73 m2 before infection to 78.9±8.7 mL/min/1.73 m2 after the disease (p≥0.05). These findings suggest a trend towards decreased kidney function in young patients with moderate COVID-19 severity. However, normoalbuminuric compared to creatinine was significantly higher than normal after COVID-19. Urine tests indicated a trend of decreased renal glomerular filtration rate. Clinical symptoms included high temperature, weakness, cough, and, in some cases, liquid stools. Laboratory findings revealed significant deviations in hematocrit, neutrophil, and eosinophil concentrations. Parallel tests focusing on cystatin C and beta-2 macroglobulin are recommended to assess kidney function and identify potential dysfunction.