Urgent diagnosis of hereditary angioedema in the ICU and ED: the critical role of rapid complement testing – a case report

This case highlights the importance of considering HAE in patients presenting with unexplained slowly-evolving angioedema without urticaria, when traditional histamine-directed therapies fail, especially when airway compromise is imminent. Awareness that C4 levels are universally low during HAE attacks, is key. C4 testing is widely available and prompt communication with biochemistry or immunology laboratories facilitates rapid turnaround. Urgent presumptive diagnosis facilitates appropriate emergency management and prompt referral for definitive diagnosis and management. Early identification and management of HAE can significantly reduce morbidity and mortality associated with this condition.