Diarrhea-associated hemolytic uremic syndrome is characterized by hemolytic anemia, thrombocytopenia, and acute kidney injury secondary to enteric infection, typically Shiga toxin-producing Escherichia coli. Shiga toxin 2 is able to activate alternative complement pathways; therefore, the aim of the study was to analyze C3 as a predictor of clinical courses in patients with diarrhea-associated hemolytic uremic syndrome. We hypothesized that the patients with increased complement activation at admission suffered from a more severe course. We retrospectively analyzed data of 33 pediatric patients between 1999 and 2015 in the Czech Republic. We tested the association of a C3 concentration with biochemical parameters and the clinical data reflecting the severity of the disease. We found significant correlation between the initial C3 and the duration of renal replacement therapy (r = - 0.62, p = 0.0001) and the initial glomerular filtration rate (r = 0.36, p = 0.026). Patients with C3 < 0.825 g/L needed renal replacement therapy and also had significantly more renal complications (p = 0.015).Conclusion: Based on our study, decreased C3 concentrations can be used as one of the risk factors that can help predict the need for acute dialysis and a more severe course of disease in children with diarrhea-associated hemolytic uremic syndrome. What is Known: • Shiga toxin modulates the function of complement regulatory proteins and thus contributes to complement activation in patients with diarrhea-associated hemolytic uremic syndrome. • Risk factors that can predict the need for acute renal replacement therapy and poor outcome in patients with diarrhea-associated hemolytic uremic syndrome are mainly the combination of oligoanuria, dehydration, leukocytosis, high hematocrit > 23%, and neurological involvement. What is New: • A lowered concentration of C3 at the time of initial presentation of diarrhea-associated hemolytic uremic syndrome was associated with more severe renal failure and the need for renal replacement therapy along with the development of more extra renal complications. • Decreased C3 at admission can predict complicated course of diarrhea-associated hemolytic uremic syndrome.

Department of Pediatrics 2nd Faculty of Medicine Charles University Prague and University Hospital Motol Prague Czech Republic

Paediatric Clinic University Hospital Brno Medical Faculty of Masaryk University Brno Czech Republic

The Clinic of Paediatrics Faculty of Medicine University of Ostrava University Hospital Ostrava Ostrava Czech Republic

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