Extrinsic Hemolytic Anemia

Question 1

Immune and Non-immune mechanisms

Answer 1

Immune:
- warm and cold agglutinin anemia
Non-immune:
- systemic disease
- mechanical destruction - fragmentation hemolysis
- hypersplenism
- toxins/drugs

Question 2

Fragmentation hemolysis presentation

Answer 2

• varying degrees of anemia

- evidence of fragmentation - schistocytes

Question 3

Alternative names

Answer 3

Micorangiopathic hemolytic anemia

Thrombotic microangiopathy - thrombotic changes and frequently thrombocytopenia

Question 4

Etiology of extrinsic hemolytic anemia

Same as Microangiopathic increased destruction in Thrombocytopenia

Answer 4

HUS-TTP
DIC
HELLP

Question 5

DIC

Answer 5

Activation of coagulation cascade
- due to release/increase of TF
- deposition of platelet thrombi and fibrin in small vessels
- mechanical shearing of red cells on fibrin strands
Causes:
- sepsis, trauma, malignancy, obstetrical complications

Question 6

HELLP

Answer 6

Hemolysis with a microangiopathic blood smear,
Elevated
Liver enzymes, and a
Low
Platelet count
- Complication of pregnancy, associated with DIC
- Can produce hepatic rupture, visual failure, seizures, and heart failure
Tx - prompt delivery of the fetus

Question 7

HUS-TTP

Answer 7

Primary platelet activation
HUS - microangiopathic hemolytic anemia, thrombocytopenia, renal failure
TTP - above plus fever and neurologic abnormalities

Question 8

Causes of HUS-TTP

Answer 8

Childhood:
- E. coli O157:H7
- Atypical HUS - acute kidney injury without diarrhea
- Congenital TTP - abnormal ADAMTS13 gene
- Acquired autoimmune TTP - autobody inhibition of ADAMTS13
Adulthood:
- Acquired autoimmune TTP - autobody inhibition of ADAMTS13
- Drug induced (a) immune mediated - quinine, (b) drug toxicity - chemotherapy
- E. coli O157:H7
- Pregnancy
- Congenital TTP - abnormal ADAMTS13 gene
- Autoimmune - SLE

Question 9

Other causes of MAHA

Answer 9

Malignant hypertension

Malfunctioning valves and cardiac assist devices