Pediatrics · Year 3 · from Pediatrics

Case 3: Hemolytic Uremic Syndrome

Patient Demographics

  • Age: 2-year-old female
  • Sex: Female

Chief Complaint

"She's been having bloody diarrhea for five days and now she's barely peeing and looks pale."

History of Present Illness

A 2-year-old girl is brought to the emergency department by her parents with a five-day history of bloody diarrhea. The diarrhea began as watery stools three days before becoming bloody. She attended a family barbecue one week ago where she ate undercooked ground beef. Over the past 24 hours, she has become increasingly lethargic, her urine output has decreased significantly, and her parents note she appears very pale. She has had decreased oral intake but no vomiting. No other family members are ill.

Physical Examination

  • Vital Signs: Temperature 37.4C, HR 145 bpm, RR 28/min, BP 102/68 mmHg, SpO2 99%
  • General: Pale, lethargic toddler, irritable when examined
  • HEENT: Pale conjunctivae, dry mucous membranes
  • Cardiovascular: Tachycardic, regular rhythm, flow murmur present
  • Respiratory: Clear to auscultation, mild tachypnea
  • Abdomen: Mildly distended, diffuse tenderness, hyperactive bowel sounds
  • Extremities: Cool extremities, capillary refill 3 seconds, no edema
  • Skin: Pallor, petechiae on trunk and extremities
  • Neurologic: Lethargic but arousable, no focal deficits

Laboratory Findings

  • CBC: Hemoglobin 6.8 g/dL, WBC 18,000/uL, Platelets 35,000/uL
  • Peripheral smear: Schistocytes (fragmented RBCs), helmet cells present
  • Reticulocyte count: 8% (elevated)
  • BUN: 65 mg/dL (elevated)
  • Creatinine: 3.2 mg/dL (markedly elevated)
  • LDH: 2,500 U/L (markedly elevated)
  • Haptoglobin: <10 mg/dL (undetectable)
  • Urinalysis: Blood 2+, protein 1+
  • Stool culture: Pending; Shiga toxin assay positive
  • Coagulation studies: PT and PTT normal

Diagnosis

Hemolytic uremic syndrome (HUS) - typical/diarrhea-associated

Clinical Reasoning

This child presents with the classic triad of HUS: microangiopathic hemolytic anemia (low hemoglobin with schistocytes on smear), thrombocytopenia, and acute kidney injury, following bloody diarrhea caused by Shiga toxin-producing E. coli. The history of undercooked ground beef consumption is consistent with E. coli O157:H7 infection. The elevated LDH and undetectable haptoglobin confirm hemolysis, while normal coagulation studies help exclude DIC. Typical (diarrhea-associated) HUS is distinguished from atypical HUS, which occurs without preceding diarrheal illness.

Management

  1. Supportive care: Primary treatment is supportive; no specific therapy alters disease course
  2. NO ANTIBIOTICS: Antibiotics may increase toxin release and worsen outcomes
  3. Fluid and electrolyte management: Careful fluid balance; avoid both dehydration and overload
  4. Dialysis: Indicated for severe oliguria, hyperkalemia, or uremia; initiate peritoneal or hemodialysis as needed
  5. Transfusion: RBC transfusion for symptomatic anemia (Hgb <7 g/dL or hemodynamic compromise)
  6. Platelet transfusion: Avoid unless active bleeding (may worsen microvascular thrombosis)
  7. Monitoring: Strict intake/output, daily weights, twice-daily chemistry, neurologic checks
  8. Prognosis: Most children (>85%) recover renal function; some develop chronic kidney disease

Clinical Image

Image Description: Peripheral blood smear demonstrating schistocytes (fragmented red blood cells) and helmet cells characteristic of microangiopathic hemolytic anemia in hemolytic uremic syndrome.

Source: Wikimedia Commons URL: https://commons.wikimedia.org/wiki/File:Schistocytes_in_HUS.jpg License: CC BY-SA 3.0

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