Change in INR reading

[Chris1945]

Hi again everyone, for the past 5 years my INR checks have been spot-on at 2.5, yesterday, it was 3.2 and I can't think of anything I've done differently diet-wise, so Warfarin reduced from 5mg to 4mg and another check next week. Maybe this is relatively common and I'm worrying too much! I've considered changing to Apixaban a few times but never acted upon it, however, how does one know if blood is too thick or thin on this drug or does it work in a different way? Thanks in advance for your help.....x

[Hidden]

Just to put your mind at rest, anticoagulants do not thin the blood. They contain chemicals which prevent the blood from clotting and this is why it may take twice as long for nosebleeds and cuts to stop bleeding, so the term “blood thinners” is wrong and misleading.

Take a look at the AF Association webpage and find out all you need to know about anticoagulation.

heartrhythmalliance.org/afa...

Unlike Warfarin, there are no regular blood tests but you will need blood tests to make sure your kidneys function correctly and these are repeated at least annually, sometimes twice a year......

[Chris1945 in reply to Hidden]

Thanks for the reassurance Flapjack will check out the link and decide what to do from there....it's all a bit of a minefield! x

[BobD Volunteer]

Flapjack beat me to it other than to say don't worry about a small increase. I would worry about a 1 mg change in dose myself as I know I would drop too low at that rate so good you are only being one week down the line. Could have been anything or nothing. maybe something different you ate so relax. I've been on warfarin fifteen or more years and yes now and again I get a rogue reading.

[fairgo45 in reply to BobD]

Bob what about someone like me on my usual dose of 3 then after 10 days its 1.5 I've been on antibiotics would that make a difference?

How would you alter the dose to bring it up to at least 2 and what foods would help?

[BobD Volunteer in reply to fairgo45]

Antibiotics will change you INR for sure. Ignore foods. If you self test try an additional mg for a couple of days and re-test. Remember being over carries less risk that under unless you go over 5. Strangley I have found antibiotics put mine up but we are all different and I guess ditto antibiotics.

It is also worth mentioning that a few years ago we had a presentation at HRC on INR by the UK leading expert who stated that in his opinion the vagaries of testing meant that to be sure we were properly covered we should be aiming for a range of 2.5 to 3.5 not 2 to 3. Most medical centre computer systems seem unable to grasp this and also have the shortcoming of not recognising trends. As a result we often find people drop out of range either end when a modicum of common sense would have seen dose altered before it happened. For that reason I have always lied to my phlebotomist about what I take and she has always ignored that she knew and I can't remember that last time I dropped out of range Happy days.

[fairgo45 in reply to BobD]

Yes I self test so I will up the dose and retest in a few days thanks for the advice

Now if only you could tell me why as a permanent Afibber I'm suddenly getting runs of tachycardia lasting 4 hours 100 to 120 beats a minute it's very scary I'm.not used to it what should I take to slow it down a beta blocker?

[BobD Volunteer in reply to fairgo45]

The wonderful world of arrhythmias. Tell me about it. Sixteen years and counting and still learning. Get rid of one and another pops up. At least I know its still beating. Lol 😁

[Chris1945 in reply to BobD]

Thanks Bob, that's so reassuring....will keep fingers crossed for a back to normal reading next week....x

[Wightbaby]

Yes, I agree with Bob on this......been on Warfarin for over 5 years, and, for me, INR is usually 'in range' though not spot on.

I hope the drop to 4mg was just for one night?

When i have the odd rogue reading, its often due to the slightest change in my diet, (i.e. Christmas or holidays) which is usually VERY consistent.....or of course on the odd occasion a cold or virus. The highest mine has been (only once!) was 3.9......by dropping 1 mg it was back below 3 within a week.

I tend to ignore the computer and tweak my dose myself.

3.2 is really not high at all......

hope this helps.

[Chris1945 in reply to Wightbaby]

Thanks, the reduction to 4mg is not just for one night, it's for a week so next Wednesday will be the next check and fingers crossed, it will be back down to 'normal'!

[Wightbaby in reply to Chris1945]

Goodness, If I dropped from 5mg per night to 4mg per night, my INR's would plummet.........do let us know what the result is next week..!

[Chris1945 in reply to Wightbaby]

Okay, thanks for tha...., in the meantime, I'll try not to worry that mine has plummeted too!😳 Yes,I will post result when I have them.. x

[Chris1945 in reply to Wightbaby]

Update....INR checked again yesterday and after last reading (and change of warfarin from 5mg to 4mg) it's gone down from 3.2 to 2.1 with another check again in a week's time as it's now too low! I've racked my brains for reasons as to why it's changed so much after being so constant, but to no avail. Only difference I can think of is that I was eating more dark chocolate than usual and I'm using coconut milk in coffee now...are those possible factors? Anyway, ever onwards....thx for everyone's support, no idea what I'd do with out this website....😍

[StuJ019]

I have the occasional blips my INR went up to 3.2 for no apparent reason so went back to a weekly test kept on the same dose of 5.5 it went down to 2.8 so kept on 5.5 and last week was down to 2.7 so kept on same dose 5.5 and to be checked in two weeks time. I have been on warfarin for nearly five years and have these blips now and again. I would not worry as long as your surgery are keeping you in check. I’m sure it will settle down again. Good luck.

[MarkS]

As you've had such a good record at staying in range on warfarin, I would not rush to change. The NOACs are better when warfarin is poorly controlled, but with your record of what must be at least 90% in range, warfarin outperforms the NOACs.

Do you self-check? I do and check my INR every week or so and adjust by 0.5mg. As Bob says, I just tell the anticoag clinic what they want to know.

[ILowe]

A change from 2.5 to 3.2 really is a small change, believe you me. My statement is strong, so deserves good support.

1/ There is a margin of error, even in venous blood samples, variously estimated at 10-15%. This means the difference could be less, could be more.

2/ There is a natural biological background variation. Surprisingly, this has never been quantified by the medical profession (I would love to be proved wrong). It would be difficult to establish nowadays because of the desire to intervene. From my own (published) evidence it can be higher than 2. That means, in your case, a jump from 2.5 to 4.5 then a lower figure could be normal, just a fluke.

3/ As has often been said on this forum, any INR below 5.0 is reasonably safe, so, let nature take its course.

4/ Leading researchers have proposed that whenever you get a fluke result, even a high one, the first reaction is to do nothing for 1-2 weeks to allow the body to autocorrect. eg ncbi.nlm.nih.gov/pubmed/196...

5/ There is some evidence, and good reasons to believe that attempts to achieve a narrow range can provoke the opposite which is swings with a greater variation. Meier DJ, Seva S, and Fay WP 2007. A comparison of anticoagulation results off patients managed with narrow vs. standard international normalized ratio target ranges.