Table 1. Classification and... | American Society of Hematology

Table 1.

Classification and characteristics of thrombotic microangiopathy syndromes.

Category	Clinical Features*	Mechanism	Treatment
*Clinical features listed are in addition to microangiopathic hemolytic anemia and thrombocytopenia.
**Conditions associated with autoimmune ADAMTS13 deficiency and idiopathic TTP include certain autoimmune disorders, pregnancy, and ticlopidine.
Idiopathic TTP	Coombs negative, without DIC or other conditions associated with secondary TTP. Severe renal failure is uncommon. Specific conditions** that may coexist with idiopathic TTP are discussed in the text.	Autoimmune ADAMTS13 deficiency in a majority of patients.	> 80% response to plasma exchange. May benefit from immunosuppression.
Secondary TTP	Associated conditions include cancer, infection, hematopoietic stem cell transplantation, solid organ transplantation, chemotherapy, certain drugs.	Mechanisms are mostly unknown. ADAMTS13 deficiency is rare.	With few exceptions, responses to plasma exchange are unlikely. Treatment and prognosis are dictated by the specific associated conditions.
Diarrhea-associated HUS (D+HUS)	Acute renal failure, often oliguric, preceded by bloody diarrhea.	Endothelial damage by Shiga toxin–producing E. coli. ADAMTS13 deficiency is rare.	No demonstrated efficacy of plasma exchange.
Atypical HUS	Acute renal failure, often oliguric, without a prior diarrheal illness.	Complement regulatory protein defects in at least 50% of patients; ADAMTS13 deficiency is rare.	No demonstrated efficacy of plasma exchange, except possibly for factor H deficiency.

Category	Clinical Features*	Mechanism	Treatment
*Clinical features listed are in addition to microangiopathic hemolytic anemia and thrombocytopenia.
**Conditions associated with autoimmune ADAMTS13 deficiency and idiopathic TTP include certain autoimmune disorders, pregnancy, and ticlopidine.
Idiopathic TTP	Coombs negative, without DIC or other conditions associated with secondary TTP. Severe renal failure is uncommon. Specific conditions** that may coexist with idiopathic TTP are discussed in the text.	Autoimmune ADAMTS13 deficiency in a majority of patients.	> 80% response to plasma exchange. May benefit from immunosuppression.
Secondary TTP	Associated conditions include cancer, infection, hematopoietic stem cell transplantation, solid organ transplantation, chemotherapy, certain drugs.	Mechanisms are mostly unknown. ADAMTS13 deficiency is rare.	With few exceptions, responses to plasma exchange are unlikely. Treatment and prognosis are dictated by the specific associated conditions.
Diarrhea-associated HUS (D+HUS)	Acute renal failure, often oliguric, preceded by bloody diarrhea.	Endothelial damage by Shiga toxin–producing E. coli. ADAMTS13 deficiency is rare.	No demonstrated efficacy of plasma exchange.
Atypical HUS	Acute renal failure, often oliguric, without a prior diarrheal illness.	Complement regulatory protein defects in at least 50% of patients; ADAMTS13 deficiency is rare.	No demonstrated efficacy of plasma exchange, except possibly for factor H deficiency.