Warfarin and INR levels?

Would anyone have any idea why, after months of being at a stable INR of around 2.5 to 2.8, my INR has dropped to 2.1, despite no real change of diet etc.

I test myself weekly, only going to the surgery for testing every couple of months as directed, tested last week at 2.4 and this week at 2.1.

I spoke to my GP yesterday but he didn't seem concerned as long as I didn't drop below 2. Of course I understand the recommended range is between 2 and 3, but taken into account all that has been written and said about inconsistencies I prefer to be at the higher end of the scale.

Any thoughts/comments gratefully received.


12 Replies

  • Hi Ray

    Although always in range, mine always varies slightly, I usually test fortnightly. Haven't hot a clue what I do differently, but as everything seems to affect warfarin I did wander if the pollen count may affect it

    Just a thought


  • I've found I've had to increase my dose by about 0.5mg with the approach of summer. I'm not sure why - possible more Vit K in green leaves due to the sun?? As soom as I get any dip I increase my dose slightly and v.v. Did you increase your dose when your INR dipped to 2.4?


  • Are you monitoring yourself, Mark? I like the idea of doing this but how to tie it in with my GP/Cardio treatment, remains a mystery.


  • Hi David,

    Yed I do self monitor. I don't find it a problem at all tying it in with any other treatment. It just goes on independently of everything else.


  • Hi Mark,

    No I didn't increase my dose at 2.4, but this week I've upped it with it dropping to 2.1 by a little and will test again in a day or two. As previously said the GP didn't seem concerned, but it's not him that has the same risk as me!!! This backs up my reason for spending money on the self testing kit, especially as the surgery has got me on ten week intervals.

    Taken on board your comment re green leaves and sun, as well as Eileen and the pollen count. Nice to see some sun anyway.

    Take care


  • I'm with MarkS on this. I often try to anticipate a drop in INR, which can happen fairly frequently and for no obvious reason. I don't know if this is peculiar to my own clinic but their computer doesn't seem to do that so if current INR is above 2.0, even though it might have been in recent decline, they'll still tell you to stay on current dose and come back in a month. Unsurprisingly, you're then probably outside therapeutic range which is quite simply dangerous. As soon as I see a decline, I arrest it with an additional 0.5mg and, to date I successfully maintain (100% of the time) therapeutic range at the high end of 2 which is where I want it to be. I should emphasise, I wouldn't make any change to the clinic's recommended dosage in excess of 1mg without telling them but I do feel that we know our own bodies and at times we have a duty to ourselves to 'assist' in the management of our dosages.

  • You may well of eaten one of the many antidote foods out there. There does seem to be million and one things that make it move up or down but as long as you are within range it should not be such a problem.

  • It's my feeling that exercise keeps my INR down and lack of exercise sends it up significantly.

    I agree with leelec about the surgery policy. At mine, if your INR is 2.0 it is in range and is deemed to be OK. Last time I went, my INR was 2.1 and a month before it was 2.3. No dose adjustment and six weeks to the next appointment. Where am I now? Somewhere around 1.8 I suspect. I have to address the warfarin topic with my GP sometime and if it is decided that I should continue with warfarin, I will definitely buy a monitor of my own and self test far more regularly than they suggest.

  • When I was on Warfarin it was quite clear that the cardiologist and the GP had different ideas about what constituted in range. My range was 2.0-3.0 and I mostly struggled around the bottom figure or below. Cardiologist was unhappy with anything below 2.5 and had a policy of recommending the maximum dose I could tolerate. GP was happy with anything over 2.0 and kept me on the lowest dose possible to achieve it. I was taking different strength tablets on different days of the week and had numerous drug interactions. I was told by hospital and GP that warfarin didn't really go with some of the other drugs but that I should take it anyway.

  • Interesting, Mrspat. You'll be glad your warfarin days are behind you.

    I definitely feel that to be protected one needs an INR in the region of 2.4 - 2.6.

  • G'day Ray,

    I've been on 70 day INR tests for a while now and have had a fairly constant Coaguchek reading of around 2.4 to 2.6. Now, all of a sudden it has dropped to 2.1 - have no idea why, nor do I bother about it. My problem is I use a Coaguchek self monitoring device and monitor my own INR and initially bought this because when I lived in Surrey I drove buses and the constant shift work made it just about impossible to keep a surgery appointment for tests. My surgery in those days had each nurse and computer using the same device and software.

    Now I've moved to Cornwall my surgery doesn't indulge in these devices and draws blood from the arm, bottles it and sends it away for the usual analysis. I still use my device and monitor the surgery, and twice now I have used the Coaguchek device to prove to the surgery that they are in error when giving me my next dose. Which the surgery has agreed with and revised my doseage.

    For my money the Coaguchek device is the more accurate. On my last test my device gave the reading of 2.1 while the blood from the arm technique gave a reading of 1.8. Both blood tests were within 20 minutes of the other. Mind you this wasn't helped by my forgetting my dose two nights before my INR blood letting. Even so, I don't bother about it and if I was seriously worried I'd do what Mark does and slip myself 0.5mg dose extra and not tell anyone, although I do keep my own records on INR software I have on my laptop and anything I do I make file notes of the event, safer that way :-). Now the surgery have dropped me back to 14 day tests.


    Aussie John

  • Interesting isn't it , all really substantiating my view self monitoring is the way to go.

    I've had similar experience with the blood having been sent to the lab as you Aussie John, so agree I would trust my coaguchek machine, however I worry about the attitude from various GP's about acceptable levels which prompted me to pose my question.

    As I said earlier I've tweaked my dose of my own back especially as I don't have any idea what caused the sudden change and I feel happier if it is at the higher end of the scale.


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