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High INR in a blood test

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High INR in a blood test
Last update: 28/05/2021

What is a high INR in a blood test called?

  • High INR

What is the normal INR in a blood test?

If you need to know which are the INR reference ranges or you require more information about INR in a blood test, you can visit normal INR in a blood test.

What does a high INR mean?

A high INR (International Normalized Ratio) value shows an increase in the time necessary to complete the clotting process. When there is a hemorrhage, the clotting process is activated to stop the bleeding.

INR is close related to the prothrombin time (PT). PT is one of the most important parameters measured in the coagulation screen section of a blood test. The major advantage of the INR system is that it helps alleviate confusion in the interpretation of prothrombin time (PT) results. Usually, laboratory changes thromboplastin and/or equipments used to calculate PT with has a direct impact on prothrombin time, but the INR remains constant even with such changes.

INR is usually used to monitor the dose of patients under anticoagulant therapy. The objective of anticoagulant therapy is to prevent cardiovascular disorders and thrombosis.

In healthy people not under anticoagulant therapy, a high INR value may suggest a liver disease, vitamin K deficiency or disseminated intravascular coagulation (DIC).

In people under anticoagulant therapy with warfarin (Coumadin) or acenocoumarol, values of INR over 3 mean that the dose of anticoagulants prescribed is excessive and should be reduced.

  • Mild INR increase (1.1 - 3 in adults):

    These values in people not under anticoagulant treatment are over the normal range and a visit to your doctor is recommended. It may be due to a liver disease or vitamin K deficiency. Anyway, it is better to use prothrombin time (PT) for this matter. INR is only recommended for patients under anticoagulant therapy.

    In patients under anticoagulant treatment, those who are being treated with warfarin (Coumadin) or acenocoumarol, the INR should be 2 to 3. Therefore, these values are considered to in the appropriate range.

  • Moderate INR increase (3 - 4.5 in adults):

    If you are taking anticoagulant drugs (warfarin) you should visit your doctor to adjust (reduce) the dose and avoid an INR over 3 (or 3.5 if you have a mechanical heart valve).

    In people not on anticoagulant therapy, it may be due to a liver disease or disseminated intravascular coagulation (DIC).

  • Marked INR increase (4.5 - 7 in adults):

    If you are taking anticoagulant medication, you should reduce the dose or stop it according to your doctor prescription to avoid prolonged bleeding. In addition, it may prescribe you small doses of vitamin K. There also many drugs (antibiotics for example) that may interfere the effect of anticoagulants.

    If you are not on anticoagulant therapy, values are very high and it may be due to a liver disease that requires immediate attention.

  • Severe INR increase (> 7 in adults):

    If you are taking anticoagulant medication, you should visit your doctor immediately to reduce the dose or suppress it completely. In addition, he may prescribe you vitamin K, clotting factor concentrate or fresh frozen plasma to avoid prolonged bleeding time.

    If you are not on anticoagulant therapy, it may be an emergency where there is a liver failure and it may even require a liver transplant.

Which factors can raise the INR in a blood test?

There are some health circumstances or drugs than can raise the INR in a blood test:

  • Alcohol
  • Vitamin K deficiency
  • Diarrhea
  • Vomiting
  • Drugs
    • Antacids
      • Esomeprazole
      • Lansoprazole
    • Antiarrhythmic agents
      • Amiodarone
    • Antibiotics
      • Metronidazole
      • Sulfamethoxazole
    • Anticoagulants
      • Acenocoumarol
      • Clopidogrel
      • Phenprocoumon
      • Fluindione
      • Warfarin
    • Aspirin

Which diseases can raise your INR in a blood test?

The most common diseases why the INR can be higher than normal are:

  • Disseminated intravascular coagulation
  • Hepatitis
  • Hepatitis C
  • Hepatic cirrhosis
  • Liver failure
  • Cholestasis
  • Congenital afibrinogenemia
  • Congenital dysfibrinogenemia
  • Congenital hypofibrinogenemia
  • Malabsorption
  • Purpura fulminans
  • Zollinger–Ellison syndrome

What can I do to lower the INR in a blood test?

If the INR value is higher than normal, you may follow the next tips:

  • Reduce the dose of anticoagulant therapy (warfarin or acenocoumarol). You must talk to your doctor about it.
  • Increase the intake of vitamin K on your diet. Some vegetables are rich in vitamin K such as kale, sprouts, broccoli, spinach or cauliflower.

Where can I find more information about INR in a blood test?

You can visit our pages about:

Which values are considered a high INR in a blood test?

The following values are considered to be above the normal range:

IMPORTANT: These levels are expressed in units. They are an example of a healthy man/woman of about 40 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

INR
Mild INR increase
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7
2.8 2.9 3      
Moderate INR increase
3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8
3.9 4 4.1 4.2 4.3 4.4 4.5  
Marked INR increase
4.6 4.7 4.8 4.9 5 5.1 5.2 5.3
5.4 5.5 5.6 5.7 5.8 5.9 6 6.1
6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9
7        
Severe INR increase
7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8
7.9 8 8.1 8.2 8.3 8.4 8.5 8.6
8.7 8.8 8.9 9 9.1 9.2 9.3 9.4
9.5 9.6 9.7 9.8 9.9 10 10.1 10.2
10.3 10.4 10.5 10.6 10.7 10.8 10.9 11
11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8
11.9 12 12.1 12.2 12.3 12.4 12.5 12.6
12.7 12.8 12.9 13 13.1 13.2 13.3 13.4
13.5 13.6 13.7 13.8 13.9 14 14.1 14.2
14.3 14.4 14.5 14.6 14.7 14.8 14.9 15
15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8
15.9 16 16.1 16.2 16.3 16.4 16.5 16.6
16.7 16.8 16.9 17 17.1 17.2 17.3 17.4
17.5 17.6 17.7 17.8 17.9 18 18.1 18.2
18.3 18.4 18.5 18.6 18.7 18.8 18.9 19
19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8
19.9 20 20.1 20.2 20.3 20.4 20.5 20.6
20.7 20.8 20.9 21 21.1 21.2 21.3 21.4
21.5 21.6 21.7 21.8 21.9 22 22.1 22.2
22.3 22.4 22.5 22.6 22.7 22.8 22.9 23
23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8
23.9 24 24.1 24.2 24.3 24.4 24.5 24.6
24.7 24.8 24.9 25 25.1 25.2 25.3 25.4
25.5 25.6 25.7 25.8 25.9 26 26.1 26.2
26.3 26.4 26.5 26.6 26.7 26.8 26.9 27
27.1 27.2 27.3 27.4 27.5 27.6 27.7 27.8
27.9 28 28.1 28.2 28.3 28.4 28.5 28.6
28.7 28.8 28.9 29 29.1 29.2 29.3 29.4
29.5 29.6 29.7 29.8 29.9 30   
Medically reviewed by our Medical staff on 28/05/2021

Bibliography

  • A Manual of Laboratory and Diagnostic Test. 9th edition. Frances Fischbach. Marshall B. Dunning III. 2014. Pag 159. ISBN-10: 1451190891.
  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 282.
  • Laboratory tests and diagnostic procedures with nursing diagnoses (8th ed), Jane Vincent Corbett, Angela Denise Banks, ISBN: 978-0-13-237332-6, Pag. 300.
  • Essentials of Medical Laboratory Practice. Constance L. Lieseke, Elizabeth A. Zeibig. 2012. ISBN: 978-0-8036-1899-2 Pag: 319.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 5.0.Published: November 27, 2017. U.S. Department of health and human Services. Disponible en: https://ctep.cancer.gov

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