Bleeding

Question 1

What are the requirements for secondary haemostasis in the lab?

Answer 1

Citrate - to chelate calcium

Centrifugation - to separate components to give platelet free plasma

Question 2

What is thromboplastin?

Answer 2

Phospholipid + tissue factor (factor III)

Question 3

How is the extrinsic pathway measured?

Answer 3

Prothrombin time. Patient plasma, thromboplastin, calcium.

Question 4

How is the intrinsic pathway measured?

Answer 4

Activated partial thromboplastin time. Patient plasma, partial thromboplastin (phospholipid), calcium.

Question 5

What is normal PT?

Answer 5

10-13 secs.

Question 6

What is normal APTT?

Answer 6

26-38 secss.

Question 7

What does lupus anticoagulant cause changes in

Answer 7

APTT

Question 8

What is thrombomodulin?

Answer 8

It sits on vascular endothelium with thrombin on top of it. It activates the conversion of protein C to APC, which then combines with protein S to inhibit factors Va and VIIIa.

Question 9

What does antithrombin do?

Answer 9

Inhibits factors in the intrinsic pathway.

Question 10

What does plasmin do?

Answer 10

Breaks down cross linked fibrin to FDPs including D dimers

Question 11

How do tissue plasminogen activators work?

Answer 11

Cause conversion of plasminogen to plasmin