Low INR test

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RunMartin

RunMartin

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Joined
Oct 20, 2003
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310
Location
Pendle Hill, North West, England
I have just got back from my INR test. It was 1.7 but it was 2.1 6 weeks ago - it should be between 2.0 and 3.0.
The nurse said it was too low and gave me a Herapin injection. I have been told to take 6mg of warfarin tonight instead of 4mg and come back tomorrow morning to be tested again. My INR has been as low as this before and it was corrected by slightly increasing the dosage - this was at a different hospital.

Do you think this a bit drastic? I thought the dosage was changed gradually.

I have increased my daily exercise since my last test and have competed in 6 short races and I have been doing one long run each week (I actually did a long run yesterday which was 3 hours). Is this likely to effect the INR in such a way?

Thanks

Martin
 
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Yes, exercise can drop your INR. You can go to the online coumadin calculator, input your current dose, your current INR and get a calc of what changes should be made. But testing daily won't help. It will take about 3 days for the increased dosage to show up in your INR. Retest no earlier than 48 hours after dosage increase. A one time dosage increase to your warfarin won't fix things long term, either. Especially if you have increased activity or increased vit K intake.

At 1.7 you probably should receive heparain/lovenox. And did. However, the lovenox is dosed every 12 hours, not just one shot. dosages should be 1 mg/kg of body weight for a mechanical valver, until INR hits 2.0 or better. You need an RX of lovenox to give yourself shots.
 
RunMartin said:
Do you think this a bit drastic? I thought the dosage was changed gradually.

I have increased my daily exercise since my last test and have competed in 6 short races and I have been doing one long run each week (I actually did a long run yesterday which was 3 hours). Is this likely to effect the INR in such a way?

Thanks

Martin
Click to expand...

This increase in your exercise routine could have the effect of lowering your INR. A 1.7 would make me uncomfortable and the 2mg(50%) increase should bump your INR up. To test after only a day or so after the med increasee probably will not be a meaningful INR and be careful that they don't put you on a "yo-yo". If you maintain this exercise routing, you probably will have to increse your warfarin a little. You are correct in understanding that "small" dosing changes are best, but a 1/2 dose increase may be warranted to get your INR up more quickly.
 
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Laurie is right. Testing tomorrow may very well be a waste of time. I could be wrong on this, but I think heparin/lovenox works a little different and won't effect your INR reading. Good thing to take/have until your back in range which should be a couple of days.
 
RunMartin

Thx to you and all others for posting your experience's. Very soon I will be in your shoes as surgery is later this month, for a MAV transplant and ascending aorta graft.

I like RunMartin am as well are over the top athletic. I have learned from this thread! Now I have to figure out how to save it to my desk top. Suggestions on saving this valuable thread?
 
Just figured out how to save the thread, That was easy.

Thx Hank for the simple tools!
 
RunMartin

You stated : "I have just got back from my INR test. It was 1.7 but it was 2.1 6 weeks ago - it should be between 2.0 and 3.0. "

Any idea how long your INR may have been this low?

Do you home test? If not I feel it would be advantageous.
 
Martin, as long as you are below range it is wise of the hospital to have you go back daily for the heparin shot and
to verify that your INR is not dropping any lower. Taking 6 mg tonight is fine, just don't take 6 mg daily for the rest of
the week because that will bump you to high.

We usually measure percentage increases based on the weekly dose.
If you are taking 4mg for 7 days that would be 28 mg for the week,
and a 10% increase would be a 2.8 mg increase for the WEEKLY total.
 
Your Nurse is Out of Date and does not understand how Coumadin works.

It takes 3 or 4 DAYS for Coumadin / Warfarin to become fully metabolized.
Testing TOMORROW is a Waste of Time, Money, and if she wants you to increase your dose again, or even to maintain her 50% daily dose increase, this will put you into the dreaded Roller Coaster Effect.

She SHOULD have given you a prescription for Lovenox Injections which need to be administered every 12 hours until your INR is back in range. FWIW, many of our home testers / self dosers prefer to be at the high end of their range to minimize the Risk of Stroke (i.e. 2.5 to 3.0 for a mechanical valve in the Aortic Position).

MY Dosing Guide (from AL Lodwick) recommends a 10-15% increase in the weekly dose with a recheck in 1 week based on your INR and Recommended Range.

There are several On-Line Dosing Guides also. Some have been posted here in the Anti-Coagulation Forum. Unfortunately, I don't remember the addresses (sorry).

'AL Capshaw'
 
As NormoftheNorth said in another thread, it's the 'instantaneous' INR that matters most.

The question that bdryer asked about how long it's been this low is an important one -- I don't think that clots form extremely rapidly (but I'm not sure).

I second the suggestion about doing self-testing. Although others on this forum may have gotten tired of seeing me suggest it, I'm suggesting it here, again. If you had been able to self test more frequently - rather than waiting for SIX weeks between tests - you would have been able to detect the drop below perhaps a week or two earlier, and would have been able to adjust your dosage to correct the drop. You probably wouldn't have needed heparin. Also - having the ability to do your own testing gives YOU better control of YOUR INR.

Also -- it would probably be prudent to not adjust more than 10-15% of your weekly dose. If the initial increase doesn't bring you high enough, you can always push it up another 5-10%. (Just a thought -- maybe some will have an opinion here - since your INR IS below 2.0, perhaps you should kick your dosage up 15-20%, and then drop back just 2 or 3 % if necessary, if it gets too high).
 
My usual dose is 3 mg on Saturday, Sunday, Tuesday, Thursday and 4mg on Monday, Wednesday and Friday. It has been like this for the last 6 months.

My last few tests results are:

12th April INR 2.5 dose 3.00/day
10th May INR 1.8 change dose to 3.43/day
25th May INR 2.1 dose 3.43/day
14th June INR 2.4 dose 3.43/day
12th July INR 1.9 dose 3.43/day
9th Aug 2.3 dose 3.43/day
6th Sept INR 2.3 dose 3.43/day
4th Oct INR 2.3 dose 3.43/day
15th Nov INR 2.0 dose 3.43/day
10th Jan INR 1.7 Today Herapin injection
 
RunMartin said:
My usual dose is 3 mg on Saturday, Sunday, Tuesday, Thursday and 4mg on Monday, Wednesday and Friday. It has been like this for the last 6 months.

My last few tests results are:

12th April INR 2.5 dose 3.00/day
10th May INR 1.8 change dose to 3.43/day
25th May INR 2.1 dose 3.43/day
14th June INR 2.4 dose 3.43/day
12th July INR 1.9 dose 3.43/day
9th Aug 2.3 dose 3.43/day
6th Sept INR 2.3 dose 3.43/day
4th Oct INR 2.3 dose 3.43/day
15th Nov INR 2.0 dose 3.43/day
10th Jan INR 1.7 Today Herapin injection
Click to expand...

Your INR does tend to hang at the bottom of the range which is a bit risky, but your readings have been consistent.
If your health care system prefers that you go back tomorrow for the shot and INR check that is really fine, just
don't adjust the dosing every day. Make a change based on the week, eg. 10% and stick with it.
 
Sounds like a good idea.

It looks as if your regular WEEKLY dose was 23 mg, and your INR was always hanging around 2.0 +/- .4 or so. I wouldn't be surprised if increasing to 26 or perhaps 28 per week would bring you more towards the higher (and more desirable) part of the range.

Besides - asking your doctor or the clinic questions you get from this forum should let them know that a) you're taking an active interest in managing your INR and b) you've got dozens - if not hundreds - who are also interested in seeing that your INR stays within range

(You may also consider asking about self-testing and, possibly, self management of your INR).
 
Protimenow said:
As NormoftheNorth said in another thread, it's the 'instantaneous' INR that matters most.

The question that bdryer asked about how long it's been this low is an important one -- I don't think that clots form extremely rapidly (but I'm not sure).
Click to expand...

My current understanding of the two different risks -- low INR with a mech valve risks a "thromboembolic" or "clot-throwing" event; high INR risks a "bleeding event", either from a trauma or from a ruptured aneurysm -- is that the 'instantaneous' INR matters most for bleeding events, but the longer-term average INR may be what matters most for clot-throwing events. And like bdryer and protimenow, I ASSUME that clots form slowly, and that they can also UNform slowly when INR is at or above the therapeutic range. (but I'm not sure)

Even if these assumptions are both exactly right, I'm not sure they give much helpful guidance. Our target "therapeutic range" INR is still the best overall tradeoff between the two risks, the Devil and the Deep Blue Sea. (Maybe if you're on your way up the ladder onto the roof, or about to parachute out of the plane, you could delay your ACT pills a couple of hours?)
 
The effect of warfarin is slow -- you can't just take a pill and expect INR to climb.

And, in my own personal experience, I've seen that clots CAN slowly dissolve when INR levels are raised.

The trick, I guess, is really to find the range and keep within it -- and to be careful if you're at the high end and extremely careful if you've gone over it.

I've said it many times before and will repeat myself yet again -- it is helpful to have a meter and to be able to test as frequently as you (or your anticoagulation manager) think is advisable.
 
I went to INR clinic and the INR was 1.8. I had another shot of Heparin and need to take 6 mg again tonight then back to a slightly increased dose (to take into account the extra exercise I am doing). I asked the questions of whether my INR was generally low and was told that they try to keep it between 2 and 3 and readings can vary by 0.5 during the day. If it drops below 1.8 then that is when Heparin is used. The nurse seemed happy that my previous readings had been fairy constant and that the drop in INR over the past two months was probably to do with the increased exercise. I go back next Tuesday for my next test.
 
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RunMartin said:
I went to INR clinic and the INR was 1.8. I had another shot of Heparin and need to take 6 mg again tonight then back to a slightly increased dose (to take into account the extra exercise I am doing). I asked the questions of whether my INR was generally low and was told that they try to keep it between 2 and 3 and readings can vary by 0.5 during the day. If it drops below 1.8 then that is when Heparin is used. The nurse seemed happy that my previous readings had been fairy constant and that the drop in INR over the past two months was probably do to the increased exercise. I go back next Tuesday for my next test
Click to expand...

That's 'probably' an acceptable plan given your recent increase in exercise.

In the USA, "over-dosing" is no longer recommended by most knowledgable anticoagulation managers since it tends to result in the "Roller Coaster Effect". Lovenox Injections every 12 hours is often recommended until the patient's INR is back in range. Testing in 1 week is a Good Idea. That will give your body time to react to your dosing changes and will alert you reasonably quick if it should go too high.

'AL Capshaw'
 
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