Playing the Blame Game, When aHUS Masquerades as TTP and HELLP
Document Type
Conference Proceeding
Publication Date
2025
Publication Title
American Journal of Respiratory and Critical Care Medicine
Abstract
Introduction: Atypical hemolytic uremic syndrome (aHUS) is a rare thrombotic microangiopathy (TMA) driven by complement pathway dysregulation, which leads to endothelial injury and frequently causes renal failure. Differentiating aHUS from other thrombotic microangiopathies, such as thrombotic thrombocytopenic purpura (TTP) and Shiga toxin-associated HUS (STEC-HUS), is critical because a misdiagnosis could delay treatment and worsen prognosis. We present two cases of aHUS with distinct clinical scenarios.
Case Presentation: A 23-year-old woman presented postpartum with syncope, thrombocytopenia (platelets 45×10⁹/L), and acute oliguric renal failure. Laboratory findings revealed microangiopathic hemolytic anemia with schistocytes on peripheral smear. Initial management included plasmapheresis for suspected thrombotic thrombocytopenic purpura (TTP) given acute encephalopathy, however normal ADAMTS13 activity and recent delivery raised suspicion for aHUS. Following meningococcal vaccination, eculizumab therapy was initiated. After three doses of eculizumab, renal function improved significantly, enabling discharge with outpatient follow-up. The second case involved a 19-year-old man who presented with gastrointestinal symptoms following recent travel. Initial investigations revealed significant renal impairment with oliguric renal failure, thrombocytopenia (platelets 35×10⁹/L), and anemia (hemoglobin 8.2 g/dL). Plasmapheresis was attempted but discontinued due to an allergic reaction. With normal ADAMTS13 levels and negative infectious workup, including stool Shiga toxin polymerase chain reaction (PCR), the clinical suspicion shifted toward aHUS. After administering meningococcal prophylaxis, eculizumab therapy was initiated, resulting in a gradual improvement in platelet count. His clinical status stabilized, with restoration of adequate urine output, allowing for discharge.
Discussion: These cases demonstrate the diagnostic complexity of aHUS and the therapeutic efficacy of complement inhibition. The postpartum case illustrates the challenge of distinguishing aHUS from pregnancy-related thrombotic microangiopathies (HELLP: Hemolysis, Elevated Liver enzymes, and Low Platelets) syndrome, while the post-infectious presentation highlights the importance of differentiating aHUS from typical HUS. Rapid differentiation of TMA subtype remains crucial for optimal outcomes. Our experience demonstrates that timely complement inhibition, coupled with coordinated multidisciplinary care, can effectively manage this challenging condition. Further, these cases contribute to the growing evidence supporting early therapeutic intervention with eculizumab in aHUS, while emphasizing the need for standardized diagnostic approaches to expedite appropriate treatment.
Volume
211
First Page
A5907
Recommended Citation
Alnabulsi Z, Faizee F, Blazin T, Smith Z, Nair GB. Playing the blame game, when ahus masquerades as ttp and hellp. Am J Respir Crit Care Med. 2025;211:A5907.doi: 10.1164/ajrccm.2025.211.Abstracts.A5907
DOI
10.1164/ajrccm.2025.211.Abstracts.A5907
Comments
The American Thoracic Society (ATS) International Conference, May 16-21, 2025, San Francisco, CA.