Biomedical Scientist specialised in haematology here!
A lot of what others have said here are right – just thought I’d add to it.
In the UK patients taking blood thinners such as Warfarin or Heparin are monitored weekly. They will have there bloods taken weekly for INR and dosing.
A normal INR is between 1.0 and 1.5. A result lower than this will mean the blood is not thin enough and higher than this means there’s a risk of clotting.
All patients on blood thinners keep one-to-one contact which a anti-coagulation nurse. The nurse will call them when there dosage of warfarin needs to change, and equally the patient will contact the nurse should they feel they have any problems.
The example of your arm bleeding isn’t a totally accurate example of what would happen due to bleeding from blood thinners. It wouldn’t be at the point of a cut that you would find out you had a clotting issue from blood thinners.
Generally if there is a problem with clotting factors due to a too high dose of warfarin – you’d be most likely to expect an extremely large, purple bruising across the abdomen area, hense why you won’t really gain a cut and continually bleed from it as you’d already be internally bleeding.
In your example; a cut that wont stop bleeding or bled for along time would be more accurate as someone suffering from Haemophilia which is caused by a deficiency in clotting factors VIII. The patient would also bruise easily in this case.
Back to answer the blood which is too thin – if a patient is on blood thinners and there INR was below 1, the coagulation nurse would call them to change their warfarin dosage to try and bring the INR back up to around 1-1.5. If the low INR is deemed dangerous based on a patients background, health and history – if they aren’t already in the hospital they would be asked to again the clinic for treatment which may include vitamin K injections, platelet transfusion and/or cryoprecipitate
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