# A Case Report of Atypical Hemolytic Uremic Syndrome Presenting With Disseminated Intravascular Coagulation

## TL;DR

A child with atypical hemolytic uremic syndrome also had disseminated intravascular coagulation, and treatment with eculizumab led to rapid improvement.

## Contribution

This case report presents a rare co-occurrence of aHUS and DIC and suggests a potential link between complement activation and DIC.

## Key findings

- The patient met diagnostic criteria for both aHUS and DIC at presentation.
- Treatment with eculizumab led to rapid and sustained clinical improvement.
- The case supports the hypothesis that uncontrolled complement activation may contribute to DIC.

## Abstract

A previously healthy seven-year-old boy presented with clinical and laboratory findings consistent with atypical hemolytic uremic syndrome (aHUS) given thrombocytopenia, microangiopathic hemolytic anemia (MAHA), and acute kidney injury in the setting of influenza A. Notably, he also met diagnostic criteria for disseminated intravascular coagulation (DIC) at the time of presentation with clinical findings including prolonged prothrombin time (PT), markedly elevated D-dimer, and low fibrinogen. While aHUS and DIC share overlapping clinical features, they are traditionally regarded as distinct entities, with aHUS driven by complement dysregulation and DIC by the widespread activation of the coagulation cascade resulting in microvascular thrombosis, consumptive coagulopathy, and secondary fibrinolysis. The patient was treated with both supportive care and eculizumab, a terminal complement inhibitor, leading to rapid and sustained clinical and laboratory improvement without recurrence. This case highlights the diagnostic and therapeutic complexity of concurrent aHUS and DIC, lends clinical support to emerging hypotheses that uncontrolled complement activation may contribute to DIC, and underscores the value of early recognition and complement-directed therapy in atypical hemolytic uremic syndrome (HUS).