Atypical HUS - Hemolytic Uremic Syndrome Unlike typical HUS, which is shigatoxin mediated, aHUS is not typically associated with diarrhea (though possible). Think of etiology as being everything minus diarrhea (autoimmune like SLE, drugs, congenital, etc). It is complement over-activation mediated. Falling within the sphere of thrombotic microangiopathies, patients still present with anemia, thrombocytopenia, and evidence of end organ damage. The last patient I saw with this had renal, cardiac, pulmonary and liver failure. However, no neurological manifestations (as in TTP) Look for schistocytes on peripheral smear, and obtain ADAMTS13 activity to rule out TTP. aHUS has a more insidious course, higher mortality (up to 25%), vs tHUS which has more acute presentation following often bloody diarrhea and less mortality. If uncertain dx, do not delay plasma exchange. Especially if concern for possible TTP (you don't even need the ADAMTS13 level back, just treat. If this is aHUS, treat with Eculizumab (complement blockade) Long term prognosis is poor. 50% progress to ESRD, and recurrence is 50-60% in those who get renal transplant. Recurrence often managed with JustinMD @JustinMD19 #Atypical #HUS #aHUS #Hemolytic #Uremic #Syndrome #diagnosis
