AF Association
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My INR Has Drastically Dropped

Ok, so ive been on warfarin for the last 3 years (this is now the 3rd year)

The last time i went to the doctors for a blood check up was October 2015 and my INR then was 2.1.

I just went yesterday (20/01/2016) and it came up as 1.2

Now for the love of me I do not know what has caused it to decrease. Yes I eat vegetables, but no where near in excess, i eat a lot of jacket potatoes, tuna, cheese, sweetcorn, mayonnaise, chicken, rice, cucumbers, cereal - and thats pretty much it

This is very perplexing -

8 Replies

Shows the importance of more frequent testing

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Any one who read my recent posting about INR's, will know I agree with this!! Mine had gone back to 2.3 today (after 3.1 2 weeks ago)......don't think the nurse was very happy because I confessed that I had ignored the computer's suggestion that I drop the 1mg extra that I take once a week.....I was sure it would stabilise on its on, and this was because I have been on the same dose and VERY STABLE for the past 2 years, and the one time it went up to 3.1 before - no change in dose was suggested!!!

So they are keeping me on my old dose and checking again in 2 weeks.

Like dranzer1 I have no idea why they went up.......apart from going away at Christmas, so deviating slightly from usual diet!!


When mine dropped like that , which it did a few times, they then put me on weekly or fortnightly testing for while. Hope they do the same for you.

Oct to end Jan is long time.



My GP aims for 12 week testing for me - I think that is far too long. He tells me it's in the guidelines. I'm at 8 weeks at present.


My initial view is that 3 months is far too long unless you self test and can carry out additional tests in between. I do self test and have gone as long as 70 days as instructed by my clinic. However, because I self test I have the option of carrying out tests myself in between and I don't tell anyone. Just a peace of mind thing.

How many times in 3 years have you been on 3 monthly tests ? How many times in 3 years has your INR behaved in this way ? Unless it was occurring regularly I would treat it as a one off and not worry. If it was a regular feature I'd ask my GP for more frequent testing and in this regard of course you may not have a clue because you would not have done any tests within the 3 month time period. My understanding from reading various NICE papers is they reckon INR testing of 2 weeks is sensible.



Last May my apixaban was working fine, giving me the best possible protection from stroke. It was still working to 100% effectiveness through October, and today, yes it's still doing it's thing.

What's warfarin?


I think anyone on long term warfarin needs a Coaguchek monitor. I test my INR weekly and it's always in the 2-3 range. A little high and I drop 0.5mg and v.v. Keep your INR in range 90%+ of the time and it performs better than the NOACs, including apixaban!


What is your target INR? This is usually expressed as a figure, eg 2.5, or a range, eg 2.0 to 3.0. In practice, this is a VERY tight range. Many people have swings well outside this range, without changing the dosage.

I am always more concerned about a low INR than a higher INR. The key question is, is this 1.2 a fluke? Was the testing right? A doctor told me, if I suspected a fluke, to insist on a retest the next day. Abroad, you can simply go to the next lab and try again. You could self-test with the Coaguchek.

If you cannot retest the next day, then what is the safe course of action? Answer: an immediate boost of 20% for your Warfarin for 2-3 days, then normal dosage. This boosting tops up the reservoir level, and you can go back to normal dosing. With Low INR you have a lot of margin with boosting -- it really is safe. Then you test weekly for 3 weeks. If you see that it again drops very low, then the reservoir level insists on dropping. It is time for a daily dose increase of around 20%. Again, test weekly.

Remember, you must keep your lower INR above 2.0 to have any protection. On the other hand, swings above 3.0 (up to 5.0) are inconsequential.

Read this document. It is not difficult. Ask if you want to discuss it. Use it when talking to health professionals. It really is good.



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