INR self-testing

INR stands for ' international normalised ratio'.

Please note: This is a Monday to Friday service only.

The testing process

The routine testing process

• Perform capillary (finger prick) INR test.
• Record result in your yellow book.
• Email the result to the anticoagulation service: put your name and hospital number in the subject line. Aim to do this before midday.
• Do not email on Saturday or Sunday; this is a Monday to Friday service only.
• Continue present dose until you hear otherwise.
• If you have not heard within 24 hours, please send the email again.
• If you have any problems with emailing the service, please phone 01223 217127.

The urgent testing process

• Perform capillary (finger prick) INR test.
• Record result and why you have performed INR in your yellow book.
• Email the result to the anticoagulation service: put your name and hospital number in the subject line, and include in the email the reason you have tested early.
• Do not email on Saturday or Sunday; this is a Monday to Friday service only.
• If you are not contacted by mid-afternoon, please phone 01223 217127, contact your GP or attend Accident and Emergency.

High and low INR readings

Signs of a high INR

• Bleeding from gums.
• Blood in urine or stool.
• Nosebleeds.
• Bloodshot eye.
• Vomiting or coughing up blood.
• Excessive bleeding.

What should I do if I have symptoms of a high INR?

• Check your INR.
• Inform your anticoagulant service if your INR result is higher than your INR range (Monday to Friday only).
• Follow new instructions immediately.
• If out of hours, go to the hospital or inform your GP.
• Always be aware of what to look out for.
• Write any bleeding episodes in your yellow book.

Signs of a low INR

• Often there are no signs.
• Redness, tenderness, swelling and or warmth to lower limbs (may indicate a deep vein thrombosis).
• Chest pain, difficulty breathing and shortness of breath (may indicate a pulmonary embolism).
• Weakness or paralysis of extremities, impaired vision, slurred speech (may indicate a stroke).

What should I do if I have symptoms of a low INR?

• Check your INR.
• Inform your anticoagulant service if your INR is lower than your INR range (Monday to Friday only).
• Follow new instructions immediately.
• If out of hours, go to hospital or contact your GP.
• Always be aware of what to look out for.
• Write any episodes in your yellow book.

Quality control (QC) and care of your machine

• Internal – Follow the manufacturer's recommendations. Instructions should be included with your machine.
• External – The anticoagulant service request that with every tenth capillary INR sample taken on the home monitor, and used by our service for dosing the patient, must be accompanied by a venous sample taken the same day by your GP or the outpatient blood testing service for comparison.

The minimum requirement for QC is once yearly.

The outpatient anticoagulant service recommends an annual review with your GP demonstrating your INR results and warfarin doses. This review should include an assessment of the patient ensuring the benefit of anticoagulation still outweighs the bleeding risk of this therapy.

References

1. Guide for patient self-testing and the management of oral anticoagulation behalf of the BCSH Committee (2014). British Journal of Haematology
2. Fitzmaurice, D.A., Gardiner, C. Kitchen, S. Mackie, I. & Machin, S. (2005) An evidenced based review and guidelines for patient self-testing and management of oral anticoagulation. British Journal of Haematology, 131, 156-165.
3. NPSA (2007) ‘Actions that can make anticoagulant therapy safer. Patient Safety Alert 18’ (Ref 0440). National Patient Safety Agency, London.
4. T.P. Baglin, 1 D. Cousins, 2 D. M. Keeling, 3 D. J. Perry1 and H.G. Watsona for The British Committee for Standards in Haematology and National Patient Safety Agency (2006), British Journal of Haematology, 136, 26-29
5. Keeling, D & Baglin, T.P. (2011) Guidelines on oral anticoagulation with warfarin – fourth edition. British Journal of Haematology, 10, 277-285