Hemolytic Uremic Syndrome

• Clinical Presentation
• Hemolytic anemia, thrombocytopenia, and renal failure.
• 90% occur between 6 months and 5 years of age
• Watery diarrhea precedes anemia/thrombocytopenia by about a week
• Renal insult: oliguria, azotemia, hypertension
• HUS is most common cause of childhood acute renal failure
• Some have GI Sx including abdominal pain, nausea, vomiting, diarrhea.
• Neurological Sx in about one quarter of children: seizures, mental status changes.
• From cerebral microthrombi
• Lab Findings
• Elevated LDH, AST, unconjugated bilirubin (from RBC contents)
• Decreased haptoglobin (has been entirely bound by free hemoglobin)
• Thrombocytopenia around 5-100 x 10⁹/L, median 50 x 10⁹/L
• PT and PTT normal, fibrinogen normal or slightly decreased
• UA: Proteinuria, microscopic hematuria, cellular casts
• Low plasma albumin (renal loss)
• Peripheral Smear: Schistocytes, spherocytes
• Detection of causative organism in stool is definitive
• Etiology
• Toxin-producing organisms
• E. coli H0157:H7 (verocytotoxic) and 026:H11
• Shigella dysenteriae type 1 and 234
• Streptococcus
• Association with
• Poorly cooked beef, esp. hamburgers; other foods
• Contaminated pool water
• Shiga-like toxins appears to act directly on endothelial cells and possibly platelets
• Treatment
• Supportive
• Angiotensin converting enzyme inhibitors may help with renal HTN
• ? Plasma infusion or exchange
• ? IvIg
• No role for steroids
• Prognosis
• 2/3 to 7/8 of children recover completely
• 5 to 10% mortality with acute illness