Why it's done

Your doctor might recommend a prothrombin time test to:

  • Monitor the effectiveness of a blood-thinning medication that you're taking
  • Diagnose liver problems
  • Assess your blood's ability to clot before you have surgery

The prothrombin time test is one of several tests used to screen people waiting for liver transplants. That screening — known as the model for end-stage liver disease (MELD) — is a scoring system for assessing the severity of chronic liver disease.

When you have a prothrombin time test, you might also have:

  • Additional testing to assess the health of your liver, if your doctor suspects you have liver problems
  • Additional clotting-function tests, if your doctor suspects you have a bleeding disorder