Abstract
Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) which is considered life-threatening and caused by dysregulation of the complement system. Here, we report a previously healthy 8-year-old boy who presented with clinical and laboratory features of aHUS one week after viral symptoms during COVID-19 pandemic. The patient was admitted to the hospital due to symptoms of viral infection, fever, pallor, edema, and changes in urine color. Meanwhile, initial laboratory findings showed anemia, thrombocytopenia, elevated levels of creatinine and blood urea nitrogen (BUN). Despite fluid and electrolyte management, the patient developed symptomatic volume overloud and pulmonary edema which led to the necessity of receiving hemodialysis and plasmapheresis. Following genetic tests, a homozygous pathogenic variant in the CD46 gene, encoding membrane cofactor protein (MCP), has been revealed. The patient initially responded to plasmapheresis but experienced a relapse requiring hemodialysis, additional plasmapheresis, and ultimately eculizumab therapy to inhibit terminal complement activation. Therefore, this case highlights that COVID-19 may trigger complement-mediated TMA and emphasizes on the importance of prompt diagnosis, genetic evaluation, and targeted complement inhibition in aHUS.