Coagulation

Question 1

What is the differential for a prolonged aPTT?

Answer 1

• Congenital hemophilia: VIII, IX, XI deficiency
• Acquired hemophilia A
• vWD
• patient on heparin
• lupus anticoagulant
• FXII or prekallikrein deficiency (no bleeding)
• pre-analytic issues (underfilled tubes, etc.)

Question 2

What is the differential for a prolonged PT/INR?

Answer 2

• warfarin (or rat poison)
• vitamin K deficiency
• congenital FVII deficiency
• FVII inhibitor

Question 3

What is the differential for prolonged aPTT and PT?

Answer 3

• combined deficiencies from both extrinsic and intrinsic pathways
• deficiencies of common pathway: FX, FV, II
• fibrinogen disorders
• DOACs
• cirrhosis
• sepsis
• DIC
• erythrocytosis!

Question 4

What would you expect to see at 0 min and 60 min on a mixing study in a patient with a lupus inhibitor?

Answer 4

Mixing study fails to correct at both 0 and 60 min

Question 5

What would you expect to see at 0 min and 60 min on a mixing study in a patient with an acquired inhibitor?

Answer 5

Mixing study initially corrects (or near corrects) at 0 min, but then prolongs at 60 min

Question 6

What are the 3 tests to diagnose antiphospholipid antibody syndrome (APLA)?

Answer 6

• lupus anticoagulant
• anti-beta2-glycoprotein
• anticardiolipin

Question 7

What acquired bleeding disorder is associated with APLA?

Answer 7

• prothrombin deficiency (factor 2)

Question 8

What are limitations in the use of PFA-100 in diagnosing platelet disorders?

Answer 8

• test will be abnormal if Hct <30 or plt <100
• assay must be run within 4 hours of sample draw
• requires whole blood, not plasma

Question 9

What are 2 acquired bleeding disorders associated with plasma cell dyscrasias?

Answer 9

• acquired vWD (MGUS)
• acquired FX deficiency (amyloidosis)