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. 2015 Jun 1;50(2):73–82. doi: 10.5152/tpa.2015.2297

Table 4.

Tests used in the differential diagnosis of atypical HUS

Primary step
Screening for STEC in diarrhea (+) subjects→negative→low probability of STEC-HUS
ADAMTS13 activity→normal→TTP is excluded
PT, aPTT, fibrinogen→normal→DIC is excluded
Pneumococcus antigen and Streptococcus pneumoniae in cultures→negative→Pneumococcus-related HUS is excluded
H1N1 and influenza→normal→H1N1 and influenza-related HUS is excluded
Blood homocysteine, urinary and blood MMA→normal→hereditary cobalamin defect is excluded
Serum C3 and C4→C3↓ and C4 normal→alternative complement pathway defect is considered
Secondary step
Anti-CFH antibodies→positive→anti-CFH antibody HUS
CFH, CFI, CFB levels
CFH, CFI, MCP, C3 and CFB mutations
Tertiary Step
Wide mutation screening
a

PTT partial thromboplastin time; C3: complement 3; C4: complement 4; CFB: complement factor B; CFH: complement factor H; CFI: complement factor I; DIC: disseminated intravascular coagulation; HUS: hemolytic uremic syndrome; MCP: membrane cofactor protein; MMA: metyl malonic acid; PT: prothrombin time; STEC: Shiga-toxin producing E. coli; TTP: thrombotic microangiopathy