E. coli ) Genetic (complement dysregulation) Prodrome Bloody diarrhea (usually) None (usually), or upper respiratory infection Frequency ~90-95% of cases ~5-10% of cases (Rare) Recurrence Rare (usually one-time) Common (chronic/relapsing) Prognosis Good recovery with supportive care High risk of ESRD, dialysis, death Main Treatment Supportive (fluids, dialysis) Eculizumab (complement inhibitor) Detailed Breakdown Typical HUS (STEC-HUS) Epidemiology: Primarily affects children under 10, often after consuming contaminated food. Mechanism: Shiga toxins enter the bloodstream, bind to endothelial cells, and cause thrombosis (clotting) in small vessels. Outcome: Most children recover well with supportive treatment. ashpublications.org +2 Atypical HUS (aHUS) Epidemiology: Can affect all ages, often familial or sporadic. Mechanism: Uncontrolled alternative complement pathway activation leads to system-wide endothelial damage, particularly in the kidneys, but can affect the brain and heart. Management: Requires rapid initiation of complement inhibition therapy (e.g., eculizumab) to prevent irreversible organ damage. Complications: High rates of chronic kidney disease (CKD) and end-stage renal disease (ESRD). National Institutes of Health (.gov) +4 When to Suspect aHUS Atypical HUS should be suspected if a patient has TMA symptoms (anemia, low platelets, kidney damage) but tests negative for Shiga toxin and possesses normal ADAMTS13 activity (to rule out TTP). ScienceDirect.com +1 Note: Some experts argue for abandoning "atypical HUS" in favor of more specific terms like "complement-mediated TMA," as it better reflects the underlying mechanism. ScienceDirect.com This is for informational purposes only. For medical advice or diagnosis, consult a professional. AI responses may include mistakes.
While aHUS can be triggered by an environmental insult (e.g., infection, pregnancy, surgery, certain medications), the fundamental problem is an intrinsic failure to regulate the complement cascade. This leads to systemic, recurrent, and progressive thrombotic microangiopathy, with a predilection for the kidneys but often affecting other organs such as the brain, heart, and gastrointestinal tract. The clinical presentation is variable and can lack the diarrheal prodrome typical of STEC-HUS. The prognosis for aHUS before the modern era was grim, with up to 50% of patients progressing to end-stage renal disease (ESRD) or death within the first year of diagnosis. Furthermore, aHUS is characterized by a high rate of recurrence, especially after kidney transplantation—indeed, the disease frequently destroys the transplanted organ unless the underlying complement dysregulation is addressed. typical vs atypical hemolytic uremic syndrome