PROTHROMBIN TIME (PT) TEST

Question 1

Early coagulation test developed by

Answer 1

Dr. A.J. Quick

Question 2

Evaluates the function of Extrinsic & Common Pathway

Answer 2

PROTHROMBIN TIME (PT) TEST

Question 3

Major Use of PROTHROMBIN TIME (PT) TEST:

Answer 3

Monitor Warfarin (Coumadin) Anticoagulant Therapy

Question 4

Vitamin K antagonist, which means it blocks the action of vitamin K

Answer 4

Warfarin

Question 5

Factor that Produced in liver

Answer 5

Factor II (Prothrombin)

Question 6

PRINCIPLE OF PT

Answer 6

✓ The hemostasis pathway is activated when damage occurs to blood vessel endothelium or to tissue.
✓ The extrinsic pathway is activated by tissue thromboplastin (factor III) in the presence of calcium ions.
✓ Factor X, a proenzyme, is converted to the enzyme Xa, which in turn converts prothrombin to the enzyme thrombin.
✓ Thrombin then acts on fibrinogen to form fibrin monomers that make up the initial clot
✓ Anticoagulated (N) Plasma + PT Reagent → Fibrin Clot

Question 7

Contains a commercial preparation of tissue thromboplastin and calcium chloride, substitutes for the tissue thromboplastin and calcium ions (Ca++) that are coagulation activators of the extrinsic pathway.

Answer 7

PT Reagent

Question 8

When PT: Prolonged, it can cause

Answer 8

Deficiency in Extrinsic or Common Pathway

Question 9

PROTHROMBIN TIME (PT) TEST Reference Value:

Answer 9

3.2% Citrated Plasma: 10-13 SECONDS

Question 10

Calculated value that allows standardization of prothrombin time reporting among different laboratories.

Answer 10

PROTHROMBIN TIME (PT) TEST International Normalized Ratio (INR)

Question 11

Assigned by the manufacturer to each reagent lot is used with the prothrombin time to calculate the INR

Answer 11

PROTHROMBIN TIME (PT) TEST International Sensitivity Index (ISI)

Question 12

PROTHROMBIN TIME (PT) TEST Reference Value: INR

Answer 12

1.0 – 1.4