What does it mean when my prothrombin time blood test is high, compared to normal or low?

Can mean Vit K low.: If prothrombin time blood test is high, without other high levels, it can mean a vitamin k deficiency or warfarin use. Vitamin k helps in the function and viability of factors ii, vii, ix, and x and these affect prothrombin time. If there are other levels altered, it could be a factor v, or x deficiency, disseminated intravascular coagulation (dic), or liver failure. See your doctor to be sure.