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Table 7 Clinical presentation of the various subgroups of hemolytic uremic syndrome and thrombotic thrombocytopenic purpura and investigations to confirm diagnosis

From: Atypical hemolytic uremic syndrome

Age at onset and clinical presentation Probable diagnosis Investigations to confirm diagnosis
Neonatal period
Severe jaundice
Porto colour urine without major hematuria
Consanguineous family and/or similar symptoms or neonatal death in siblings
Congenital TTP
(Upshaw-Schulman syndrome)
ADAMTS 13 deficiency (< 10%) without anti-ADAMTS 13 antibobies
Mutation in ADAMTS13 (autosomal recessive)
Neonatal period-< 6 months
Failure to thrive, feeding difficulties, hypotonia ± developmental delay
Consanguineous family
Methyl-malonic aciduria-associated HUS Hyperhomocysteinemia, hypomethioninemia, methyl-malonic aciduria
Mutation in MMACHC (autosomal recessive)
< 2 years
Invasive S.pneumoniae infection (proven or suspected): pneumonia, meningitis, septicaemia, especially if empyema or subdural collection
HUS due to Streptococcus pneumoniae False positive Coombs test
Positive cultures (blood, CSF) or PCR
Positive T-activation test (exposure of the Thomsen-Friedenreich antigen on red blood cells) supports the diagnosis
> 6 months-5 years
Diarrhea ± melena during the last 2 weeks
Endemic region of STEC or Shigella dysenteriae infection
(Shigella dysenteriae- HUS in endemic regions)
Stool or rectal swab: culture for STEC (Mac Conkey for 0157:H7); PCR for Stx
Serum: anti-LPS antibodies against the most common serotypes in the local country
Adolescents and adults
Central nervous system manifestations
No or mild renal involvement
Autoimmune context (SLE, APLS, thyroiditis)
Immune TTP ADAMTS 13 deficiency (< 10%) with anti-ADAMTS13 antibodies
From birth to adolescence and adult age
No prodromic diarrhea or prodromic diarrhea but any of the following:
- age < 6 months or > 5 years
- insidious onset
- relapse of HUS
- suspicion of previous HUS
- previous unexplained HUS
- post-transplant HUS
- pregnancy (post-partum) HUS
- non synchronous familial HUS
Complement-aHUS Complete investigation of the complement system
  1. HUS, hemolytic uremic syndrome; TTP: thrombotic thrombocytopenic purpura; ADAMTS13: A Desintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13; MMACHC: methylmalonic aciduria and homocystinuria; CSF: cerebro-spinal fluid; PCR: polymerase chain reaction; STEC: Shiga-toxin producing Escherichia coli; Stx: Shiga-like toxin; LPS: lipopolysaccharide