Prothrombin Time (PT)

1. Add 0.1ml of thromboplastin to a 75x10mm test tube - warm for 2 min at 37°C.
2. Add 0.1ml of plasma and incubate for 1 min.
3. Add 0.1ml of warm calcium chloride (CaCl₂) and simultaneously start a stopwatch to time the clot formation.

During this period the tube is tilted 3 times every 5s until the clot forms.

The result should be compared with a control plasma sample measured at the same time.