Getting to grips with warfarin

After being diagnosed with AF December 2015 and taking until 8 February for my INR to reach 2.5 my clinic extended my visits to once every two weeks. My average warfarin dose is 3.6mg. As I was leaving the country for six weeks (and do so at least three times a year) we bought a Coaguchek XS for self testing. So far so good.

On the journey to Spain I developed a nasty fluey bug - lots of coughing and aching joints, which lasted about eight days. A couple of days ago I tested my INR - 4.6! I emailed my results to the surgery followed by a phone call - they had not received the email and I wasn't able to resend during surgery hours. What to do? My husband did a fair bit of research on the internet and as I am well outside the therapeutic range the advice (from medical sites) was skip a dose, which I did last night.

I had no absolutely no idea until now that illness could affect INR readings. And I now see that even this skipped dose may well take five days to show on my INR reading. Unless some of you lovely helpful people on this forum know better?

18 Replies

  • I have had a couple of episodes of high INR and like you missed a dose. I did revert to my normal reading of between 2 and 3 in about 3 days. Try not to worry as although 4.6 sounds high I think it is not considered dangerous.

    I too have coaguchek.

    Have you asked about the newer anticoagulants. I have just changed to apixaban. If you travel a lot this is much easier as no more INR, testing etc

  • Thank you - I hadn't thought about the new anticoagulants as I haven't had any ill-effects from warfarin and didn't want to change for no good reason.

    I wasn't too alarmed about the INR reading, more about the fact that that in spite of reading upon every aspect of AF since my diagnosis less than three months ago I don't remember seeing anything about illness affecting the INR level - or maybe I just need to get used to reading the very small print in everything related to AF!

  • Yes to the last point / question!!! It can have weird and wonderful and unexpected effects!!!

  • That is AF can have weird and wonderful and unexpected effects!!!

  • Up to INR 5 should not be dangerous.

  • Thank you Bob - I wasn't too worried, just more alarmed about a 2.1 swing in under two weeks with no obvious (to me) reason.

  • But you gave a very good reason. You had a virus! If you also had antibiotics or have to at any time then you must get regular checks as this will alter INR as well.

  • Before my ablation, even without being ill and not eating green veg and salads, I could get swings of up to 2.5 in a week!!!

  • Thank you Bob - still learning...!

  • I test every week with my coaguchek. I also self manage - i.e. adjust the warfarin myself. If I did have an illness I would test every other day.

    Do you ensure you have a regular amount of Vit K every day? I take a Vit K2 pill every day and it stabilises my INR beautifully.

  • My understanding is Vitamin K and vegetables containing it are to be limited when on warfarin. Are you sure you should be taking a Vit K supplement ? Check with your doctor.

  • My GP hasn't a clue (now that's a surprise!) but my EP is very much in favour. There's been quite a lot of research on this and restricting Vit K is the last thing you should be doing on warfarin.

    The key is to have a constant dose of Vit K, either by eating the same food every day (boring) of taking tablets. I can then eat whatever I want. Vit K2 is the most effective type as it reduces the risk of atherosclerosis.

  • So your warfarin dosage must be really high to off set the vitamin K you're getting from both the supplement AND eating whatever you want? This flies in the face of everything I've been told and read on this site. Good luck!

  • Thanks. I take 8.5mg p.d. That compares with 7.5mg before I started taking the K2. I've been using it for about 6 years now and have 99% TTR. The advice to avoid Vit K is pretty old fashioned now. Vit K is an essential vitamin not just for blood clotting but to ensure calcium ends up in the right place (i.e. your bones and not your arteries).

  • Thank you Mark - read all of your posts and accompanying evidence and am convinced - Vit K2 on order! I have learned something else too - take more testing strips than needed when going away - I thought I would only be testing once a week.

  • Irene's post is probably a good reminder to people in that if they get a virus or go onto antibiotics then they should phone and bring forward their next INR test if it is a long time before it is due.

  • You can get INR checks while on holiday in Spain. One of my neighbours is give a list by his INR nurse of ones in the area or Island that he is going to.

  • That is really interesting - we are in a remote area but when we visited the clinic in the nearest small town last year we both had excellent treatment (for another viral bug). We didn't even have to show our EHIC card.

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