Hemostasis Labs

Question 1

What is a normal platelet count?

Answer 1

150,000-450,000

Question 2

What platelet count is associated with thrombocytopenia?

Increased bleeding risk?

Spontaneous bleeding?

Answer 2

Thrombocytopenia: <150,000

Increased bleeding risk: ~<50,000

Spontaneous bleeding: ~<20,000

Question 3

What components form the extrinsic coagulation pathway?

Answer 3

• tissue thromboplastin -> factor VII -> common
• calcium

Question 4

What components form the intrinsic coagulation pathway?

Answer 4

• subendothelial collagen -> factor XII -> factor XI -> factor IX-> factor VII -> common
• calcium

Question 5

What pathway does PT measure?

Answer 5

Extrinsic:

-factor VII (PT; less letters, less factors)

Common:

• factors II, V, X
• fibrinogen

Question 6

What pathway does PTT measure?

Answer 6

Intrinsic:

-factors XII, XI, IX, VIII (PTT; more letters, more factors)

Common:

• factors II, V, X
• fibrinogen

Question 7

How would you assess the common coagulation pathway?

Answer 7

look at both PT and PTT, they both measure common pathway so if they are both effected it is likely a defect in the common pathway

(could also be two defects, one in each direcet and indirect)

Question 8

Which test measures the effects of heparin?

Answer 8

PTT (heparin commonly abbreviated to Hep; 3 letters with 3 letters)

Question 9

Which test measures the effects of coumadin?

Answer 9

PT

Question 10

What is INR?

Answer 10

International normalized ratio

PT times vary based on materials used.

INR is a ratio between the PT of tested blood and PT of a control sample in order to standardize the PT results