Hemolytic uremic syndrome

Hemolytic uremic syndrome is a disorder marked by red blood cell destruction, low platelet counts, and acute kidney injury. It can follow infection or arise from complement-system dysregulation.

Thrombotic microangiopathy: A group of disorders in which small-vessel clots damage blood cells and organs. Hemolytic uremic syndrome is one clinical form of this small-vessel injury.
Microangiopathic hemolytic anemia: Anemia caused by red blood cells breaking apart as they pass through damaged small vessels. It accounts for the hemolysis in the syndrome’s defining triad.
Thrombotic thrombocytopenic purpura: A thrombotic microangiopathy commonly caused by severe deficiency of the ADAMTS13 enzyme. It can resemble hemolytic uremic syndrome but requires urgent plasma exchange.
Eculizumab: A monoclonal antibody that blocks complement protein C5. It is used to control complement-mediated disease in atypical cases.
Hemolytic uremic syndrome associated with pregnancy: Hemolytic uremic syndrome arising during pregnancy or the postpartum period. Pregnancy-related cases require distinguishing complement-mediated disease from other obstetric emergencies.
Shiga toxin: A bacterial toxin that injures cells by disrupting protein synthesis. In typical cases, toxin-mediated endothelial injury triggers small-vessel clotting.
Thrombocytopenia: A platelet count below the normal range. Platelet consumption in small-vessel clots produces this core laboratory finding.
Disseminated intravascular coagulation: Widespread activation of blood clotting that consumes platelets and clotting factors. It can cause hemolysis and thrombocytopenia, but coagulation tests often help distinguish it.
Dialysis: Treatment that replaces some kidney functions by filtering waste and excess fluid from blood. Severe acute kidney injury may require temporary kidney support.
Pneumococcal hemolytic uremic syndrome: A form of hemolytic uremic syndrome associated with invasive Streptococcus pneumoniae infection. This uncommon infectious subtype has a different trigger from Shiga toxin-associated disease.

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