Hemolytic Uremic Syndrome Differential Diagnoses

Updated: Jun 25, 2019
  • Author: Sombat Muengtaweepongsa, MD, MSc; Chief Editor: Amy Kao, MD  more...
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DDx

Diagnostic Considerations

Atypical HUS (aHUS) is a genetic-related subtype. It is previous known as diarrhea-negative subtype. As the matter of fact, diarrhea is not uncommon in aHUS anymore. Therefore, the term diarrhea-negative HUS is no longer accepted. This genetic defect causes predispose to develop aHUS via mostly alternative pathway of immune complement system. The other noncomplement-associated genetic defect in aHUS includes mutation of diacylglycerol kinase epsilon (DGKE) and deficiencies in Cobalamin C. It is an extremely rare disease with incidence of just between 0.5 and 2 per million. Although aHUS is commonly found in very young children especially age under 2 years old, it may be presented in older children and adult. [62, 64]

Genetic defect in aHUS

Complement-associated

  • Mutations in Factor H (FH)
  • Mutations in Factor I (FI)
  • Mutations in Factor B (FB)
  • Mutations in Membrane Cofactor Protein (MCP/CD46)
  • C3 Mutations
  • Antibodies Against Complement Factor H
  • Thrombomodulin Mutations
  • Noncomplement-associated
    • diacylglycerol kinase epsilon (DGKE) Mutations
    • Cobalamin C

Potential characteristics of aHUS include:

  • lack of infection-associated cause
  • non-synchronous HUS in a family member
  • recurrent disease
  • a prolonged relapsing/remitting course
  • indolent course of illness
  • onset prior to age 6 months

Differential Diagnoses