A 59-year-old woman presented with accelerated hypertension, acute renal failure, hemolysis, and encephalopathy, leading clinicians to diagnose atypical hemolytic uremic syndrome (aHUS), according to a 2015 case report published in the American Journal of Case Reports.
The patient’s encephalopathy did not improve with initial antihypertensive medication, prompting further investigation that ultimately revealed aHUS. The case highlights the diagnostic challenges associated with aHUS, particularly when it presents with symptoms atypical of the condition. AHUS is a rare, life-threatening disorder characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Unlike typical HUS, which is often triggered by Shiga toxin-producing Escherichia coli infections, aHUS stems from dysregulation of the complement pathway.
Recent research, including a case report published in February 2025, underscores that aHUS can manifest primarily as severe hypertension, further complicating diagnosis. Researchers at Moscow State Medical University reported a case where severe hypertension was the predominant initial symptom. The report, published in the Clinical Case Report section of the journal International Clinical Case Reports, emphasized the importance of early recognition to initiate complement-targeted therapy.
The 2025 case report noted that early intervention is critical to improving clinical outcomes and preventing irreversible organ damage. The authors, Dr. Igor Petrov, and Dr. Anastasia Smirnova, highlighted the necessity for clinicians to consider aHUS in patients exhibiting acute renal impairment and severe hypertension without a clear underlying cause.
A separate case study, detailed in a 2024 report from the University of Michigan, too noted the overlap between malignant hypertension and thrombotic microangiopathy, further illustrating the diagnostic difficulties. The study, published in the Journal of the American Society of Nephrology, emphasized the importance of swift adoption of life-saving treatment within a multidisciplinary team.
The American Heart Association published a case study in 2023 describing a “worrying and puzzling case of hypertension” that also pointed to the challenges in differentiating thrombotic microangiopathy associated with malignant hypertension.
aHUS is related to genetic mutations in the alternative complement pathway, leading to a distinct pathophysiology that can be tricky to distinguish from other thrombotic microangiopathies.
