INR level via lab draw vs. fingerstick test

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kolyur

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Received my On-X aortic valve last week, now I'm home recovering and my mind has turned to INR testing. My surgeon is a big advocate of home testing and I purchased a Coaguchek unit based on this advice (still on the way).

Initially I'm on 5mg of warfarin per day and he wants three INR tests done per week (M-W-F) for several weeks until things stabilize. Since I don't have my machine yet I went to the hospital lab to get my first check done. The nurse said that it was my choice whether they do a blood draw or fingerstick-style test to determine the level, but she said for new patients they recommend the blood draw until the testing frequency is reduced. Does anyone here agree with this? From what I've read, it seems like the home machines produce results fairly consistent with lab values. I'm not looking forward to getting my arm stuck eight more times... any opinions?

Thanks.
 

dick0236

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Either test normally shows the same INR result +/- a tenth, or so, of a point .....and they will seldom be the same. Like you, I don't like the blood draws and I would opt for the finger sticks....and only get a draw for a comparison if you get an weird INR via finger stick.
 

MrsBray

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My visiting nurse did finger sticks for the first two weeks I was home. When her time was up and I had to go to the lab for a blood draw, I was miffed. Get up, get dressed, find someone to drive me, wait in line to register, wait in the waiting room, have a full blood draw, and still not know the results? No sir. I did that until I could drive myself to the doctor office, which is in the same building as my cardiac rehab gym. My GP desperately wants to take over my INR management, but they do a full blood draw and can't give feedback right away. I go to my cardiologist's office and see the "coumidin nurse" about every 5 weeks (less if I'm having issues). We get a number right away, and she changes my dose if needed. I can ask her questions and get recommendations. Yes, I pay about $25/visit, and it's worth it to me. I"m in an out with a number in 10 minutes or less.
 

D1GGY

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I was goign 3 times a week now down to 1 time a week. Just got stable and currently on 6mg of Warfarin. I was up to 4.0 and had to lower my dosage. I wasn't even aware of a finger check. I prefer the blood as I can check results online here in Canada. I guess this is to me the only downfall of a mechanical valve.. I have started to scan on the inside on elbow where they have been drawing the blood.
 

pellicle

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Hi

Welcome and glad you are doing well.

kolyur;n870485 said:
Received my On-X aortic valve last week, now I'm home recovering and my mind has turned to INR testing. My surgeon is a big advocate of home testing and I purchased a Coaguchek unit based on this advice (still on the way).
Well that's just about the first time I've read that, fantastic and qudos to them!


Initially I'm on 5mg of warfarin per day and he wants three INR tests done per week (M-W-F) for several weeks until things stabilize.
wow ... that's a bit over zealous. I think that is a bit frequent, Too frequent to be of any use and so frequent that there is a very good chance that you'll have trouble stabilizing because there will be temptation to over correct your dose all the time.

Since I don't have my machine yet I went to the hospital lab to get my first check done. The nurse said that it was my choice whether they do a blood draw or fingerstick-style test to determine the level, but she said for new patients they recommend the blood draw until the testing frequency is reduced. Does anyone here agree with this?
not really ... but I do agree that now and then (probably especially the first two or three tests to get both done so you can baseline and get good knowledge of just how different one is from the other

From what I've read, it seems like the home machines produce results fairly consistent with lab values. I'm not looking forward to getting my arm stuck eight more times... any opinions?
they do, and you can find quite a few posts of mine here on exactly how close they are, the published tests. If you are interested PM me and I can send you some PDF's by email for reading if you like

Hope all goes smoothly

:)
 

pellicle

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Hi

D1GGY;n870496 said:
...I wasn't even aware of a finger check.
that's sad ... I'm not surprised, there are still a few of the old timers out there who want to lock you into them ...
I prefer the blood as I can check results online here in Canada.
I prefer my own machine, because 1) it keeps the records in its internal memory 2) I keep my own records so I can check any time I want, even when there is no internet


I have started to scan on the inside on elbow where they have been drawing the blood.
not quite sure what this means, but yes, the damage to the vein from over sampling by vein draw is going to happen ... seems that they don't give any thought to that ... its not their vein after all ... right?

:)
 

D1GGY

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pellicle;n870501 said:
Hi



that's sad ... I'm not surprised, there are still a few of the old timers out there who want to lock you into them ...


I prefer my own machine, because 1) it keeps the records in its internal memory 2) I keep my own records so I can check any time I want, even when there is no internet




not quite sure what this means, but yes, the damage to the vein from over sampling by vein draw is going to happen ... seems that they don't give any thought to that ... its not their vein after all ... right?

:)
I meant started to scar.. hurts more when they get the same spot twice. The thing with checking my levels if its up or down I never know the correct formula to increase or decrease the warfarin..
 

D1GGY

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pellicle;n870511 said:
Happy to help you if you like. PM me

Here is a blog post of mine to get you started

http://cjeastwd.blogspot.com/2014/09...ng-my-inr.html
This si awesome, I linked my wife to it. Shes liek my side nurse haha. I checked ebay and these deff are not a cheap device. I see Cardiologist on the 29th and see what he states. I have a feeling i know what to do in form of taking meds.. If its high drop dose until stable and low up it a few mg a week. I know there a formula for this just not sure the correct way and hope to figure it all out.
 

D1GGY

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pellicle;n870511 said:
Happy to help you if you like. PM me

Here is a blog post of mine to get you started

http://cjeastwd.blogspot.com/2014/09...ng-my-inr.html
Pellicle, this is amazing and im sure once my wife reads that blog we will be purchasing a kit so I can self test. Beyond informative. Great job. if I have to do thsi for life might as well make it easy on myself. Like you I have a doctor who calls every 2-3 tests and might up dosage or down it. Have to take time off work to sit at clinic and wait. I am able to check results on line now and starting to get a good feel for what I should be taking in mg a day. I am currently at 6mg a day. My last INR was 4.2 and I want to be between 2.5-3.5 im told. Just went for bloodwork today and currently waiting on the results.
 

kolyur

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pellicle, thanks for the link to your great blog post. I especially liked the tip about using a rubber band as a "finger tourniquet"--I will be doing this for sure. They were lancing my finger in the hospital to keep track of my blood glucose and I noticed that this never produced much blood--maybe not enough for an INR check.

Received my Coaguchek and strips today so I'm anxious to try it out.
 

pellicle

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Hey guys

Glad it was helpful.

I have (at the moment) three posts on INR management

http://cjeastwd.blogspot.com/search/label/INR

That link finds all articles with the label INR, so as I ad more they will appear in chronological order (most recent first) there.

BTW D1GGY there really isn't a formula worth a dann that works without you needing a genetic test for your cytochrome types. However it's no biggy as once you are see your own reactions you can soon make judgments.

The absolute key to this is rigor, document and refer to your results.
Do not make quick assumptions about what makes what effect , they will no doubt be wrong because there are natural ups and downs (although some lucky bastards seem to have very small variance, I don't know why).

The information in the goldilocks dose is the most helpful for advanced students :)

And don't forget, lance the side not the pad of the finger. I've been lancing the same finger at the same point for years now and I can no longer feel the prick. You don't want to lose feeling on the fingertip :)

Lastly I've been measuring for a few years now and over time the cost of the machine is insignificant.

But strips online and save a bundle. The coaguchek had a great internal quality control system and there are no fake strips to plague you :)
 

pellicle

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PS
If accessing those links by phone be aware that modern phones alterr the link and add a parameter ?m=1 to the URL. Forcing a delivery in mobile view. If you send that to someone on a real computer (laptop or desktop) they will want to see the PC view.

Change the 1 to 0 and reload or just erase back to ...html (leave html intact)
 

kolyur

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So I used my Coaguchek XS for the first time this morning. Followed the instructions to the letter and got an INR of 4.4. This scared me since my INR had been hovering around 3 since I got home from the hospital. So I went to the hospital lab and had them do a blood draw test... 3.2, whew.

Went back home and tried the Coaguchek again... 4.8 this time! Any ideas on why there would be such a discrepancy? I was expecting a few tenths but sheesh, a whole 1.5 points??? I can't imagine what I could be doing wrong. I'm using Accu Chek Softclix lancets now, although I had used the provided Coaguchek lancets for the first test.

In both cases I washed my hands with warm water and used pellicle's rubber band trick to ensure a hanging drop of blood.
 

dick0236

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You're right....there should not be that much difference between self and lab testing. Sounds like you are doing the test correctly. I use the Coaguchek XS and have never experienced that much difference between self and lab draws. Did you buy your meter from the manufacturer, Roche Diagnostics or an authorized dealer......or from a source like ebay? Did you put the new chip that came with the strips into the meter? Are the strips expired? I have an 800 number for Roche Diagnostics Tech Services 1-800-428-4674 (24 hours/day, seven days/wk.). They can help get you on the right track.
 

kolyur

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Thanks... I will try calling the 800 number. I bought mine on Amazon from [what appeared to be] a reputable seller. When I received it, it looked to be in "new" condition as advertised. I could be mistaken but I don't think any ol' joe can buy these directly from Roche in the USA; you have to be either a doctor or part of their monthly-fee program which I wasn't interested in. Mine says something like "for sale to physicians only" on the front of the box.

I bought the strips from the same seller and they were in sealed containers, expiration 10/2017. I was careful to use the code chip as directed. I'd be surprised if they manufacture enough of these that there would be counterfeits floating around. Other than the INR result, absolutely nothing in the device or packaging suggests that I don't have the "real deal."

I can probably return it but that puts me back at square one with home testing.
 

dick0236

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Sounds like you have done everything correctly. When all else fails.........stick your wifes, or friends, finger. Assuming they are not on ACT their INR should read 1.0 +/- .1 or .2. I do this to my wife every six months or so just to prove the accuracy of my meter.
 
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pellicle

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Hi

kolyur;n870555 said:
...
Went back home and tried the Coaguchek again... 4.8 this time! Any ideas on why there would be such a discrepancy? I was expecting a few tenths but sheesh, a whole 1.5 points??? I can't imagine what I could be doing wrong. I'm using Accu Chek Softclix lancets now, although I had used the provided Coaguchek lancets for the first test.

In both cases I washed my hands with warm water and used pellicle's rubber band trick to ensure a hanging drop of blood.
firstly, the code chip is like plugging in a thing ... it either works perfectly with the strips or the machine gives you an error of invalid code.

ok ... next, a couple of detail questions (cos that's where the devil always is).

did you observe the 15 second rule? (from the manual) This rule is to ensure that from lance moment to application moment there is no more than 15 seconds passes. The reason for this rule is that coagulation begins once the blood knows that coagulation is needed. Changing the time between when that starts and when the machine thinks it starts can be a significant issue.

how long did you apply the band for before lancing? Again, in seconds or in a longer time? When you watch the video note that the entire video is 45 seconds long. Time is a strange thing, when you're doing something you've never done before what seems like an age can be seconds ... or (because you're distracted) an age.

how different was the environment when you measured? Like was one place hot and the other cold? This shouldn't make so much difference but it may.

I don't know why but when I started out my measurements were off ... after a few times I then got much tighter.

The key ingredient is consistency. My wife tried baking stuff that her Grandmother used to bake. Her Grandmothers words were " well you just throw in a bit of htis and a bit of that and put it in the oven" ... needless to say that was a complete balls-up leading to much angst. She then bought a highly accurate scale and went nuts on accuracy. The result was that time after time she made the best cinnamon rolls on the planet.

http://cjeastwd.blogspot.com/2012/02/cardamom.html

So now that you've done it and know what is happening, watch my video again and compare what you see to what you're doing. Its always difficult watching a training video in what you've never done before. So watch it again and see.

A good idea is to set up the phone and record your self ... that way you actually can see (when you play it back) exactly the time measurements and exactly what you did (not what you thought you did).

I understood (like a year after I started) that in Australia Roche was supposed to send someone to train me ... huh ... like that happened. Anyway, they sent me a packet of 12 strips to "say sorry" and compensate me.

The key to getting consistent and accurate results is to be consistent and accurate in what you do.

Lastly, I'll mention that it may just be that when you measure your wife that you don't get 1 .. the INR is an International Normalised Ratio ... the key word there is Normalised. This means an average of the clotting times of un-anticoagulated folks. There is of course natural variations in that.

Let us know how you go
 

pellicle

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ouh yeah

one other point. There can be variations between Labs and the machines (in my case I don't normally see more than 0.2 or 0.3 difference, you're seeing nearly 1.6 which is too much.

However if I understand you you're seeing 4.4 then 4.8 between your measurements yes?

This suggests to me that your consistency is good. I'd look to reagents that the lab is using. "Using A Lab" is not in itself a "gold standard" as many factors can come into play in the process between vein draw and technician getting a reading. The labs don't like to let you in on this. Often staff don't like to let on they have not followed (VERY STRICT) protocols on handling the sample:

For instance in Australia most hospitals follow this:

Test within 2 hours of drawing the sample.
* If it will be longer than two hours, centrifuge the tube (3000 rpm),
* Pull the plasma off into a second tube,
* centrifuge that tube,
* pull the plasma off (except for the bottom 0.5 mL or so) into another tube.
* Freeze.
*Transport frozen.
now perhaps you begin to see why lab testing is not actually a gold standard and why it can give errors (lots of points in the chain for failures)

If you are interested I can send you a (sorry I only deal in) peer reviewed journal article showing that different reagents (the specific mixture of chemical used to assist in timing the binding of thrombin) showing that for the same blood sample one reagent (innovin) was giving INR = 3.4 and another reagent was giving 4.4 ... so within the range you are seeing btw

so yes, the numbers are rubbery aren't they :)
 
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