Hemolytic Uremic Syndrome (HUS)

Etiology:

Most common cause: Shiga toxin-producing E. coli (STEC, O157:H7)

Other causes: Drugs, complement defects, pregnancy

2. Pathogenesis:

Toxin-mediated endothelial damage → Platelet activation & microthrombi

RBC destruction → Microangiopathic hemolytic anemia (MAHA)

Kidney damage → Acute renal failure

3. Clinical Features:

Triad:

1. Hemolytic anemia (schistocytes on smear)
2. Thrombocytopenia
3. Acute kidney injury (AKI)

Bloody diarrhea (in STEC-HUS)

4. Treatment:

Supportive care (hydration, dialysis if needed)

Avoid antibiotics in STEC-HUS (can worsen toxin release)

Eculizumab (if complement-mediated HUS)