Case series of acute kidney injury in children with SARS-CoV2 associated multisystem inflammatory syndrome

PURPOSE: In the first part of 2021 in Khimki regional hospital was eight-times increase of hemolytic-uremic syndrome (HUS) in children vs 2020. There are some data on association of HUS and COVID-19 in the literature. Our aim to describe case series of HUS in children with SARS-Cov2 associated multisystem inflammatory syndrome (MIS-C). METHODS & MATERIALS: We developed 8 children, age 1-11 yrs. (Me 4,5), 3M/5F. All had anemia (Hb 58 - 105, Me 83,8 g/l), thrombocytopenia (45 -136, Me 84*10(9)/l) and kidney injury (azotemia, diuresis decrease, reduced GFR). RESULTS: In anamnesis nobody had COVID-19, SARS-Cov2 RNA (oropharyngeal swab) was negative. 6 had anti-SARS-Cov2 IgG. 3 patients had antibody inversion during hospitalization. That means, they developed acute kidney injury (AKI) in early convalescence period of COVID-19. 6 children had fever, vomiting and diarrhea in anamnesis. 1 had only myalgia, 1 had transient hemorrhagic rush. All children had SIRS: ESR acceleration (15-43 mm/h), CRP increase in 6 cases (not more 5 norms), elevated ferritin (307-648 mkg/l) and D-dimer (3,24-8 mkg/ml). Mixed urinary syndrome was noted: proteinuria (0,1 - 6 g/l), hematuria (RBC 6-50). 100% had azotemia: urea (12,7-65,3, Me 35 mmol/l), creatinine (74-1450,2, Me 499 mkmol/l). GFR by Schwartz formula was reduced in all cases (1,7-58,1 ml/min/1,73 m(2)). 3 had anuria, 2 oliguria. Renal replacement therapy (RRT) performed in 5 cases: 3 hemodiafiltration (HDF) only; 2 - HDF + plasma exchange (1 - 7 procedures). All children were complex treated and discharged with normal clinical urine test and creatinine level, diuresis 1,6-2,4 ml/kg/h. CONCLUSION: In MIS-C pathogenesis thrombotic microangiopathia is one of the key points. We saw elevation of HUS in children in the COVID-19-pandemia period. 6 from 8 described cases had connection of AKI with previous COVID-19. In addition, they all had SIRS markers, corresponding diagnostic criteria of SARS-Cov2 associated multisystem inflammatory syndrome.