Prothrombin Time / Quick Test

Tests the extrinsic clotting pathway — a liver function proxy.

What it is

Prothrombin time (PT) measures how long it takes for blood to clot via the extrinsic pathway. The "Quick test" (also called Quick's value) expresses PT as a percentage of normal. It depends on clotting factors produced by the liver.

Why it matters

PT/Quick is prolonged when the liver is not producing adequate clotting factors — a sign of significant liver dysfunction. It is also extended by warfarin and vitamin K deficiency. In oncology, monitoring PT ensures the liver is tolerating treatment.

How to test

Blood test (coagulation panel). Requires specialised tube (citrate).

This information is for educational purposes only. Always discuss testing and interpretation of results with your care team.

Optimal range

Quick below 70%

reduced — impaired clotting, liver dysfunction risk

70–120%

normal

How often

Each comprehensive oncology panel. Before procedures.