Hemolytic uremic syndrome

Thrombotic microangiopathy with the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Classically follows diarrhea from Shiga toxin producing Escherichia coli; atypical forms arise from complement dysregulation.

• Important cause of pediatric acute kidney injury with hemolysis. Management is mainly supportive in typical HUS and differs from TTP and DIC.

• Child with bloody diarrhea develops pallor, petechiae, and oliguria several days later.
• Labs: schistocytes, thrombocytopenia, high creatinine; PT and PTT normal.

1. Avoid antibiotics and antimotility drugs in suspected EHEC because they may increase toxin release.
2. Differentiate from TTP (more neurologic findings) and DIC (abnormal PT and PTT with low fibrinogen).
3. For atypical HUS, consider complement blockade such as eculizumab after infection is excluded.

1. Typical HUS: supportive care (fluids, dialysis if needed, red cell transfusion).
2. Atypical HUS: eculizumab or related complement inhibitors; vaccinate for meningococcus before therapy.

• Think hamburger exposure leading to HUS in hospitalized kids.
• Normal PT and PTT steers you away from DIC.

• Rising creatinine, anuria, or severe hypertension warrants urgent nephrology involvement.
• Avoid platelet transfusions unless life-threatening bleeding.

1. Microangiopathic hemolytic anemia plus thrombocytopenia plus acute kidney injury; check PT and PTT.
2. If PT and PTT normal and diarrheal prodrome present, treat as HUS with supportive care.
3. If neurologic symptoms prominent, treat as TTP with plasma exchange.
4. If PT or PTT prolonged with low fibrinogen, DIC is likely.

• Toddler after petting zoo exposure develops anemia, thrombocytopenia, and acute kidney injury with normal PT and PTT.
• Adult with recurrent episodes of microangiopathic hemolytic anemia and kidney injury without diarrhea; complement mediated HUS responds to C5 inhibition.