Coagulation Panel (Clotting)

Question 1

Partial Thromboplastin Time (PTT)

Answer 1

Tests intrinsic coagulation cascade
Not on anticoagulants: 20-30seconds

On Heparin, “therapeutic aPTT” is
1.5-2.5x normal.

Question 2

Prothrombin Time (PT)

Answer 2

Tests the extrinsic coagulation cascade
10-12 second

Question 3

International Normalized Ratio (INR)

Answer 3

It is calculated from a PT and used to monitor how well warfarin is working.

Not on anticoagulants: 0.9-1.2

Taking warfarin, “therapeutic INR 2-3”