Comparison of laboratory findings in hereditary TTP versus ABO incompatibility in neonates

All patients with hTTP had ADAMTS13 activity <5% without an inhibitor and biallelic pathogenic variants in the ADAMTS13 gene. A major difference between groups was severe thrombocytopenia in the TTP group and positive direct Coombs test in the ABO incompatibility group. Other differences included earlier and more severe jaundice, with greater likelihood of anemia, in neonates with hTTP. Most of the above differences were statistically significant with p values <0.001 (exceptions: time to maximum bilirubin, p = 0.02; presence of anemia, p = 0.01; creatinine, p = 0.02; positive direct Coombs test, p = 0.07). Parameters that were not statistically different between groups included WBC count, C-reactive protein, albumin, and hepatic alanine aminotransferase. Refer to the original paper for details and to UpToDate for additional discussions of hTTP.