Acquired Disorders of Hemostasis

Question 0

DIC definition.

Answer 0

• Disseminated Intravascular Coagulation
• response to an injury that causes activation of normal blood clotting and fibrinolytic mechanisms. What is different is that the stimulus for activation is so robust that it overwhelms the normal control mechanisms that usually limit clotting and fibrinolysis to the areas where they may actually be needed
• risk for thrombosis AND bleeding

Question 1

Thrombosis risk is ________.

Answer 1

-multifactorial

Question 2

Clinical manifestations of DIC

Answer 2

• depending on the underlying cause, patient may present with severe bleeding, thrombosis, or both. It depends on whether there is more consumption of procoagulant vs. fibrinolytic proteins
• acutely ill patients usually bleed and thrombosis is classically seen with cancer patients

Question 3

Lab findings for DIC

Answer 3

• increased PT and aPTT (but usually less so bc it is less sensitive)
• decreased platelet count
• MAHA: schistocytes and thrombocytopenia
• decrease in individual clotting factors, both pro- and anti-coagulant
• presence of fibrin degradation products (D-dimers)

Question 4

DIC treatment

Answer 4

• treat the underlying cause (infection, aneurysm, cancer, tissue damage)
• if bleeding, support with replacement of clotting factors and platelets: FFP and fibrinogen
• heparin is sometimes used in cancer-related DIC if predominant issue is thrombosis
• patient outcome depends on the success in resolving the underlying cause

Question 5

Etiology for TTP

Answer 5

-autoantibodies against ADAMTS13

Question 6

Lupus anticoagulants: what are they? what do they do in vivo vs. in vitro and why is this paradoxical?

Answer 6

• subset of phospholipid binding antibodies
• inhibit clotting in vitro if limit the phospholipid amount in test tube and therefore, prolong aPTT
• BUT in vivo, they do not inhibit clotting and therefore, DO NOT CAUSE BLEEDING as the aPTT may suggest!!
• thrombosis risk

Question 7

Anti-phospholipid antibodies and lupus anticoagulants are risk factors for __________, not _________.

Answer 7

-thrombosis, NOT bleeding

Question 8

What is a common cause of asymptomatic elongation of aPTT?

Answer 8

• antiphospholipid antibodies

- antibodies are common and usually have no recognizable pathological implication

Question 9

Antiphospholipid Antibody Syndrome

Answer 9

• presence of 1 or more types of anti-p’lipid Ab on at least 2 occasions 3 months apart and…
• thrombosis (DVT and PE, arterial thrombosis, strokes)
• pregnancy morbidity
• SOMETIMES assoc with thrombocytopenia

Question 10

Treatment for Antiphospholipid Antibody Syndrome

Answer 10

• anticoagulants as prophylaxis for thrombosis in high risk patients
• if thrombosis develops, rx with anticoagulants
• aspirin for arterial events, including frequent pregnancy losses
• duration: months-lifelong depending on clinical situation

Question 11

Name the 3 diseases discussed in this lecture and what events (thrombosis or bleeding) they place patients at risk for.

Answer 11

• DIC: bleeding, thrombosis, or both
• TTP: thrombosis
• Antiphospholipid Antibody Syndrome: thrombosis

Question 12

Conditions associated with DIC

Answer 12

• tissue damage/hemolysis
• neoplasia
• microorganisms/sepsis
• obstetrics
• miscellaneous