Protime blood test: what to know

Protime is another name for prothrombin time, often reported with an INR. The test examines part of the clotting process that depends on clotting proteins made or regulated through the liver and vitamin K pathways. A result may be requested before a procedure, during unexplained bleeding, or when someone takes warfarin. Illness, liver problems, diet, alcohol, medicines and supplements can affect the result. The meaning depends on why the test was ordered and the target set by the treating clinician.

Usually, a small blood sample is taken from a vein in the arm and no special preparation is needed unless your clinic says otherwise. Tell the team about anticoagulants, antibiotics, herbal products, recent illness and any unusual bleeding or bruising. Keep vitamin K-containing foods consistent if you take warfarin rather than making sudden diet changes, and never alter the dose without instructions. Ask when the result will be reviewed and whether another test is needed. The test can help guide care for conditions such as chronic kidney disease, coeliac disease, Crohn's disease or dengue fever, but it does not diagnose every cause of fatigue or anaemia.

Seek urgent help for bleeding that will not stop, vomiting or coughing blood, black stools, severe headache, sudden weakness, confusion, or a significant fall while taking an anticoagulant. Contact your clinic promptly about repeated nosebleeds, large unexplained bruises, blood in urine, or a result outside the range you were given. Do not wait for a routine appointment if bleeding is heavy or you feel faint.

Why was protime ordered, and what INR range applies to me? Do any medicines or supplements interact with my treatment? When should the test be repeated?