ADAMTS13 and thrombotic thrombocytopenic purpura: Currently, there are no universally accepted diagnostic criteria for TA-TMA; nevertheless, attempts have been made to create a framework for diagnosis, and broadly speaking, thrombocytopaenia, schistocytosis, increased LDH, decreased haptoglobin, a negative direct Coombs test with normal coagulation studies, and exclusion of TTP by >10% ADAMTS13 levels are accepted clinical features that warrant diagnosis (Table 2).