Journal of Medical Cases, ISSN 1923-4155 print, 1923-4163 online, Open Access
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Case Report

Volume 16, Number 7, July 2025, pages 254-258

Influenza A H1N1 Triggering Complement-Mediated Hemolytic Uremic Syndrome

Figure

Figure 1.
Figure 1. Patient’s oncologic treatment timeline. CM-HUS: complement-mediated hemolytic uremic syndrome; PR: partial response; GI: gastrointestinal; auto-HSCT: autologous hematopoietic stem cell transplantation; CAR-T: chimeric antigen receptor T-cell therapy.

Table

Table 1. Etiologies of Complement-Mediated Thrombotic Microangiopathies
 
EtiologyMechanism
HIV: human immunodeficiency virus.
Genetic mutations in complement regulators: (e.g., CFH, CFI, MCP/CD46, C3, CFB)Lead to loss of control over the alternative complement pathway, resulting in excessive complement activation, endothelial injury, and microvascular thrombosis
Acquired autoantibodies (e.g., anti-factor H)Autoantibodies inhibit function of complement regulatory proteins, causing unrestrained complement activation and endothelial damage
PregnancyIncreased complement activation triggering disease
Infections (e.g., influenza, HIV)Trigger for complement overactivation
Surgery or traumaSystemic inflammation and complement activation
Certain medications (e.g., calcineurin inhibitors)Drug-induced endothelial injury
TransplantationImmunological stress and complement activation