Talk with your healthcare provider about what your INR goal is and what it means for you. The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. Certain foods and any medicines you take may affect your results, especially if you take warfarin, heparin, or other anti-clotting medicines or are being treated for liver disease with vitamin K.
It's very important to follow your healthcare provider's instructions for having this test. You may be asked to stop eating foods that are high in vitamin K before this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.
Search Encyclopedia. International Normalized Ratio Does this test have other names? INR, standardized prothrombin time What is this test?
This results in a reduced ability to form further clots and, therefore, can cause uncontrolled bleeding from, for example, the digestive tract, respiratory tract and any skin wounds. Treatment of this condition varies depending on its underlying cause. FFP is the supernatant obtained after a unit of blood has been centrifuged. Traditionally, it has been the treatment of choice for patients who are bleeding due to over-anticoagulation with warfarin.
However, due to issues that limit its suitability, it is no longer used as widely as previously. Since FFP is a blood product, it presents the same infection transmission risks as any blood transfusion.
This risk can be limited by using FFP that has been treated with methylene blue or solvent detergent. However, treated FFP tends to only be used routinely in patients under the age of 16 years — presumably due to its increased cost. The content of vitamin K-dependent clotting factors within FFP products is variable. Some evidence suggests that, by using these products, it can be difficult to achieve a sufficient level of Factor IX to induce haemostasis.
FFP is generally not suitable for use in patients who are overloaded with fluid. Also, FFP cannot be administered as rapidly as PCC, so it is less likely to be used when a coagulopathy needs to be corrected speedily. Despite these limitations, FFP continues to be widely used for excessive anticoagulation in many areas of the UK and other countries.
This is possibly due to its low cost and the limited availability of PCC. The results of two studies 5,6 suggest that FFP could be used for major bleeding without haemodynamic compromise that is not life-, limb- or sight-threatening. This advice is echoed by the Northern Regional Haematologists Group 2.
FFP must also be administered with Smg of IV phytomenadione to ensure the production of endogenous vitamin K- dependent clotting factors. Treating patients who have received too much warfarin can be complicated.
Most patients who have a high INR but are not bleeding can be managed with simple dosage omission or oral phytomenadione and an increased frequency of INR monitoring. However, in some circumstances, warfarin can cause severe and life- threatening bleeding, regardless of whether the INR is elevated or not.
Such patients may require fresh frozen plasma or prothrombin complex concentrates to replenish their stores of vitamin K-dependent clotting factors. Br J Haematol ; British Committee for Standards in Haematology. Guidelines on oral anticoagulation: third edition. A comparison of the efficacy and rate of response to oral and intravenous Vitamin K in reversal of over-anticoagulation with warfarin. Emergency oral anticoagulant reversal: the relative efficacy of infusions of fresh frozen plasma and clotting factor concentrates on correction of the coagulopathy.
J Thromb Haemost ; Click Here. Introduction to blood clotting What is the INR? Why do we monitor the INR? How often do we measure the INR? What can interfere with the INR?
What should my INR be? How is INR tested? Laboratory testing Testing using a portable device Health facility monitoring with a portable device Home monitoring with a portable device Self-testing with a portable device Introduction to blood clotting Coagulation or blood clotting is a protective mechanism of the body against bleeding.
For more information, see Blood Function and Composition. For more information, see Anticoagulants. What is the INR? Regular monitoring is important with a drug such as warfarin because: There is a very small difference between the lowest dose that gives a good effect and the highest dose before side effects which may be serious are experienced; The doses used by different individuals to achieve the same effect can be highly variable; Several drugs interact with the medication to either increase or decrease its effectiveness; and What a person eats can also affect the action of warfarin and either increase or decrease its effectiveness.
Therefore, you should consult your doctor if you: Have a sudden change of diet leafy greens in particular ; Are taking diet supplementation; Are unwell; or Are taking other medications, including over-the-counter medications.
Common medications that interfere with warfarin include: Many antibiotics ; Some heart medications, such as amiodarone e. Aratac , Cardinorm , diltiazem e. Cardizem , Diltahexal and propranolol e. Deralin , Inderal ; Some anti- cholesterol medications, such as simvastatin e. Lipex , Zocor ; Some pain relievers and anti-inflammatories, such as celecoxib Celebrex and tramadol e.
Tramal , Zydol ; Some antidepressants , such as citalopram e. Cipramil and sertraline Zoloft ; and Some antiepileptics , such as carbamazepine e. Laboratory testing Laboratory blood testing is the traditional practice in Australia. Testing using a portable device Portable devices, introduced in the s, allow you, your doctor or another health practitioner e. Health facility monitoring with a portable device If the device is used for monitoring in a health facility, a health practitioner often a nurse conducts the blood test and records the result on your behalf.
Home monitoring with a portable device When a portable device is used for home monitoring, you usually conduct the test yourself. Self-testing with a portable device If you self-test, there are two options available: Self-monitoring: which involves your testing your INR at home, and then phoning a clinic with the result and to find if there is a need to adjust the dose and if so what the dose adjustment is; or Self-management: which involves you testing your INR at home, and adjusting your oral anticoagulant dose based on the result obtained, according to a pre-determined dose INR schedule.
More information For more information on coagulation, including information on anticoagulants, blood coagulation tests and test devices, see Blood Clotting and Monitoring. References Tripodi A. Prothrombin time international normalized ratio monitoring by self-testing. Curr Opin Hematol. A critical evaluation of the prothrombin time for monitoring oral anticoagulant therapy. Pathophysiol Haemost Thromb. Self-monitoring and self-management of oral anticoagulation. Cochrane Database Syst Rev.
Antithrombotic drugs: Part I. Optimal oral anticoagulant therapy in patients with mechanical heart valves. N Engl J Med. An analysis of the lowest effective intensity of prophylactic anticoagulation for patients with nonrheumatic atrial fibrillation. Comparison of low-intensity warfarin therapy with conventional-intensity warfarin therapy for long-term prevention of recurrent venous thromboembolism.
Optimal frequency of patient monitoring and intensity of oral anticoagulation therapy in valvular heart disease. J Thromb Thrombolysis. Warfarin: Indications, risks and drug interactions. Aust Fam Physician. Managing oral anticoagulant therapy.
Systematic overview of warfarin and its drug and food interactions.
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