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
Nov. 24, 2015
References
  1. Zehnder JL. Clinical use of coagulation tests. http://www.uptodate.com/home. Accessed Sept. 16, 2015.
  2. AskMayoExpert. Cardiac surgery excessive bleeding. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
  3. Drews RE. Approach to the adult patient with a bleeding diathesis. http://www.uptodate.com/home. Accessed Sept. 16, 2015.
  4. PT and INR. Lab Tests Online. http://www.labtestsonline.org/understanding/analytes/pt/glance.html#. Accessed Sept. 16, 2015.
  5. Bambha K, et al. Model for end-stage liver disease (MELD). http://www.uptodate.com/home. Accessed Sept. 16, 2015.
  6. AskMayoExpert. Abnormal liver tests (adult). Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
  7. Cameron JL, et al, eds. Coagulopathy in the critically ill patient. In: Current Surgical Therapy. 11th ed. Philadelphia, Pa.: Saunders Elsevier; 2014. http://www.clinicalkey.com. Accessed Sept. 16, 2015.
  8. Litin SC (expert opinion). Mayo Clinic, Rochester, Minn. Oct. 7, 2015.
  9. Prothrombin time. Mayo Medical Laboratories. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9236. Accessed Sept. 16, 2015.
  10. AskMayoExpert. Monitoring anticoagulation effects of warfarin (adults). Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2015.