Pale child with bloody diarrea

Posted on by david

Posts in this category follow the NEJM blog case discussion format, yielding dense, useful bedside information about a specific clinical issue.

Case

An 10-year old girl presented with lethargy, abdominal pain and bloody diarrea since 3 days. Her mother noted increasing paleness of the skin. Laboratory testing revealed Coombs-negative hemolytic anemia with fragmentocytes, thrombocytopenia, and elevated creatinin and ureum. A stool culture was found significant for Shigatoxin-producing E. coli (STEC).

About 90% of STEC-hemolytic uremic syndromes occure with prodromal diarrea. STEC laboratory testing may include ELISA against shigatoxin antigens, stool culture with enrichment to promote E. coli O157:H7 strain production, as well as  STEC-serotype specific IgM or anti-LPS serology.

Clinical Pearls

schistocytes

Schistocytes (fragmented RBC), also called helmet cells.

  • STEC-HUS is presenting as multi-organ disease. It may present with CNS involvement (somnolence, seizures, focal symptoms), cardiovascular syndromes (cardiac ischemia, severe hypertension), GI tract involvement (bowel necrosis, perforation, rectal prolapse, intussusception), hepatomegaly with increased LFT, as well as pancreatic disease (impaired glucose tolerance).
  • Epidemic occurences of E. coli O157:H7 are related to water ingestion, raw beef consumption and bovine contact, dairies, sprouts/lettuce, as well as person-to-person contact.

Morning Report Questions

Describe the indications for renal replacement therapy.

  1. Oliguria occurs in 60% of children, and anuria in 40%. Proteinuria and hemuria is common.
  2. Peritoneal dialysis or hemodialysis should be considered when fluid and electrolyte imbalances cannot be corrected by replacement fluids or when fluid overload compromises cardiac or pulmonary function. A ureum > 35 mmol/L or GFR < 10 ml/min may be a similar indication.
  3. Dialysis is indicated in 60% of pediatric STEC-HUS patients.

List the most important differential diagnoses to be considered in this context.

  1. In the absence of microangiopathic hemolytic anemia and thrombocytopenia, severe enteric infection with hemorrhage-prone pathogens (SSCY: Shigella, Salmonella, Campylobacter, Yseria). Renal function impairment may be pre-renal due to volume depletion.
  2. DIC may present with a similar laboratory pattern, and is indicated by prolonged coagulation tests (PT/aPTT).
  3. Non-STEC HUS. Diarrea may be present too.
    1. complement-mediated HUS (positive family history, may be preceded by infectious prodrome),
    2. pneumococcal-associated HUS (pneumonia, meningitis).
  4. Other thrombotic microangiopathic hemolytic anemias
    1. TTP (hereditary vs acquired, low ADAMTS13),
    2. drug-related TMA (typically acute onset), and coagulation-/metabolism related TMA (in infants, e.g. vitamin B12 metabolism defects).

All patient information have been changed, abstracted and anonymzed as to protect individual privacy.

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References

Tarr PI, Gordon CA, Chandler WL. Shiga-toxin-producing Escherichia coliand haemolytic uraemic syndrome. Lancet 2005.

Brodsky, R. A. (2015). Complement in hemolytic anemia. Blood, 126(22), 2459–2465. http://doi.org/10.1182/blood-2015-06-640995

Fitzpatrick, M. (1999). Haemolytic uraemic syndrome and E coli O157. BMJ (Clinical Research Ed.), 318(7185), 684–685.