Ravulizumab monotherapy for anti-CFH antibody-associated aHUS in an elderly patient: a case report highlighting individualized clinical decision-making

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy caused by complement dysregulation. Although anti-complement factor H (CFH) autoantibodies are a well-recognized cause of aHUS, their occurrence in elderly patients is rare, and optimal management in this population remains unclear. We report the case of an 85-year-old man who presented with acute kidney injury, thrombocytopenia, and microangiopathic hemolytic anemia, alongside severe hypertension. ADAMTS13 activity was preserved, and no secondary causes of thrombotic microangiopathy were identified, leading to a clinical suspicion of complement-mediated thrombotic microangiopathy (TMA). At the time of clinical decision-making, anti-CFH antibody status was not yet available;serum creatinine trends during hemodialysis could not reliably indicate intrinsic renal recovery, and hematological markers, although improving, did not clearly indicate complete resolution of hemolysis. Following an individualized risk assessment regarding plasma exchange (PEX) and immunosuppressive therapy in an octogenarian, ravulizumab was selected as the initial treatment due to its etiology-independent mechanism of action. Following initiation, hematological parameters continued to improve, and renal function gradually recovered, allowing discontinuation of hemodialysis. Subsequent testing revealed elevated anti-CFH antibody levels without pathogenic complement gene variants, confirming the diagnosis of anti-CFH antibody-associated aHUS. This case highlights that, in clinical settings with diagnostic uncertainty, ravulizumab monotherapy may be considered as an individualized initial approach in exceptional cases where PEX and immunosuppression are judged unsuitable based on clearly documented patient-specific risks, and requires careful follow-up including serial anti-CFH antibody monitoring and consideration of immunosuppression if antibody titers persist or relapse risk remains high.