Overview of Laboratory Testing and Clinical Presentations of Complement Deficiencies and Dysregulation

Historically, complement disorders have been attributed to immunodeficiency associated with severe or frequent infection. More recently, however, complement has been recognized for its role in inflammation, autoimmune disorders, and vision loss. This paradigm shift requires a fundamental change in how complement testing is performed and interpreted. Here, we provide an overview of the complement pathways and summarize recent literature related to hereditary and acquired angioedema, infectious diseases, autoimmunity, and age-related macular degeneration. The impact of complement dysregulation in atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria, and C3 glomerulopathies is also described. The advent of therapeutics such as eculizumab and other complement inhibitors has driven the need to more fully understand complement to facilitate diagnosis and monitoring. In this report, we review analytical methods and discuss challenges for the clinical laboratory in measuring this complex biochemical system.

Guidance for diagnosis and treatment of acute angioedema in the emergency department: consensus statement by a panel of Italian experts

Angioedema attacks, characterized by the transient swelling of the skin and mucosae, are a frequent cause of visits to the emergency department. Swellings of the oral cavity, tongue, or larynx can result in life-threatening airway obstruction, while abdominal attacks can cause severe pain and often lead to unnecessary surgery. The underlying pathophysiologic process resulting in increased vascular permeability and plasma extravasation is mediated by vasoactive molecules, most commonly histamine and bradykinin. Based on the mediator involved, distinct angioedema forms can be recognized, calling for distinct therapeutic approaches. Prompt recognition is challenging for the emergency physician. The low awareness among physicians of the existence of rare forms of angioedema with different aetiologies and pathogenesis, considerably adds to the problem. Also poorly appreciated by emergency personnel may be the recently introduced bradykinin-targeted treatments. The main objective of this consensus statement is to provide guidance for the management of acute angioedema in the emergency department, from presentation to discharge or hospital admission, with a focus on identifying patients in whom new treatments may prevent invasive intervention.