Coagucheck results .6 higher than blood draw,,,, word?

[hook]

I have tested my new home monitering device, and three weeks ago it was .5 higher than my blood draw, and yesterday is was .5 higher.

Roch tells me that is within an acceptable range; I call BS. Anyone else have this issue?

 

[Lynlw]

That sounds about right. There are quite a few threads about comparing your machine to the lab and why it usually is different. Heres one of them if that helps.
http://www.valvereplacement.org/forums/showthread.php?34116-INR-0.2-in-6-hours-...&highlight=apples

 

[ALCapshaw2]

My anticoagulation Clinic uses Coaguchek XS Finger Stick instruments.
They are aware that they tend to read on the high side, and the higher the reading, the greater the discrepancy.
They require a Lab Draw for any INR reading over 4.5
It is not uncommon for patients whose Coaguchek INR reading is 5.0 to have a Lab Draw Reading of 4.0

Someone recently posted that there was a Recall on XS instruments due to some cleaning process that was alledged to cause slightly elevated readings.

'AL Capshaw'

 

[lance]

Trust your XS

Trust your XS

Hello Todd
Every 6 months for years I have been required to do a comparison test between my XS and the lab.
Until recently the biggest difference was .2. Many were exactly the same.
Then the vein draws taken in the hospital were processed on-site within 4 hours and both tests were performed one after the other.
Suddenly last summer, vein draws were taken in the hospital and sent/taken to Kitchener about an hour's drive away. Test results took 3 days and it was the biggest difference ever of .8.
These vein draws not only scar my vein and I wonder what's the use. Three days to obtain results that checked a warfarin dose taken 3-4 days previously I consider useless.
Trust your XS--I've never had reason to doubt mine.

 

[Bina]

I have tested my new home monitering device, and three weeks ago it was .5 higher than my blood draw, and yesterday is was .5 higher.

Roch tells me that is within an acceptable range; I call BS. Anyone else have this issue?

If you are using the new Coaguchek XS model, make sure NOT to use rubbing alcohol on your finger or on the machine.
Follow directions carefully. Wash hands with soap and water, rinse well, dry well, and do your test as instructed.

Occasionally I do a comparison test between my monitor and a vein draw at the lab and they have been exactly the same.
Roche confirms that a .2 difference is acceptable and that if your INR is very high, then the monitor may show it as a bit higher, but a lab test can be used to confirm a very high reading.
Hook/Todd, probably your lab is using a different reagant that just happens to measure and give a lower reading.
Can you try another lab if you are still doubtful ?

 

[dick0236]

I have tested my new home monitering device, and three weeks ago it was .5 higher than my blood draw, and yesterday is was .5 higher.

Roch tells me that is within an acceptable range; I call BS. Anyone else have this issue?

I have heard that this is a frequent problem when home testing meters are compared to lab draws. Your problem now is...which method is right? There could be a number of reasons including reagents used to process results, time delay in testing or handling of sample plus testing tolerances. I have not compared my Coaguchek XS to a lab draw for over three years and that was only to confirm an abnormally high reading. Never did determine what happened to cause the "one time" spike. BTW, I seem to stay in range much, much more now that I use my own meter.

 

[Protimenow]

Bina's advice was great.
There are published reports saying that the CoaguChek XS (and S) both tend to be slightly over actual at higher values (3.5 or so and higher). If a CoaguChek XS was the meter I always use (and I don't have one yet), I'd be more concerned with consistent readings or readings that are suddenly out of range. It's important that your values are fairly consistent, and is good if you trust your meter.

I would certainly be concerned with a blood draw that may have been mishandled -- put into a glass tube, and maybe not centrifuged (if it requires this), put into the WRONG type of glass tube (the tubes used for Prothrombin testing have a special colored top), whether the blood was drawn into a plastic or a glass tube when it was taken (blood begins to coagulate if drawn into untreated glass), whether or not the blood was refrigerated when it was stored, and when it was being taken to the lab, what reagent they used at the lab, etc.

Your XS may be more reliable than the lab.

If you're concerned about the accuracy of your meter, it wouldn't hurt to run an INR of someone you know who doesn't take anticoagulants - if the value is around 1.0, this is a suggestion that the meter is accurate.

---

From my own personal experience, I have a few anecdotal things to report:

When a ProTime meter was my only meter (and one that was fairly consistent, test to test, and that I trusted), in December I had a reading of 2.9. The next day, I got hit in the head by a dishwasher (don't ask), and got a concussion. The blood test at the hospital emergency room reported a 2.92. This blood was tested within minutes of the blood draw, was probably handled properly and quickly, and confirmed the test I took the day before.

I now have a ProTime 3 (which I also trust), and a CoaguChek S. I got the CoaguChek S, brand new, because I was curious about why people on this forum prefer the CoaguChek and InRatio machines to the ProTime (and because I was able to get this meter for $40, delivered and was able to get some strips fairly affordably). When I ran tests on both the ProTime 3 and the CoaguChek S within minutes of each other, both meters reported the same result.

Your CoaguChek XS has quality controls built into the strips. It will prevent you from using strips that don't match the chip you put into the meter when you got the strips, and will do internal tests on the strips, to make sure the test you're taking is okay. Personally, I wouldn't be uncomfortable with a difference from the lab values - especially considering the high potential for mishandling of the blood sent to the lab. I would probably test an uncoagulated friend or spouse and be a lot more comfortable with the meter if the result is around 1.0 (my wife's INR with the ProTime was 0.9).

If you can find someone with another meter, or a doctor with a meter who could do just one test or who is curious enough about HIS or HER meter to want to confirm against your meter, or an anticoagulation clinic that uses a meter, doing some near simultaneous testing would help raise your confidence in the meter.

I'd just keep using the XS, recording the values every time you test, and watching for major changes from previous tests.

 

[ShezaGirlie]

If you're concerned about the accuracy of your meter, it wouldn't hurt to run an INR of someone you know who doesn't take anticoagulants - if the value is around 1.0, this is a suggestion that the meter is accurate.

I've always 'tested' my CoaguChek machines this way since I have my very own 6'5" resident guinea pig...and he doesn't mind at all..:angel:

I would pay attention though Todd, when/if you ever get a reading over 8 since that's the highest INR reading the CoaguChek will register. That's the only time I'd have a lab reading and I think my last lab reading was about 8 years ago..:thumbup:

 

[ALCapshaw2]

FWIW, I am NOT convinced that an INR reading of 1.0 on a non-anticoagulated person Guarantees that the imeter is Accurate over the ENTIRE Range of Values. To my mind, it would take 2 or more points of agreement (with some known standard) to guarantee accuracy over the usual recommended ranges (between 2.0 and 4.0)

'AL Capshaw'

 

[olefin]

Back soon after I started home testing I didn't believe my INRatio 2 meter, for I tested 7.1. Switched to other hand and tested 6.1. Switched to another batch of test strips and tested 6.8. Then tested my wife that doesn't take warfarin.... her INR was 1.1. :thumbup:

I stopped warfarin for 2 days and 4 days later was back in control.
To me it was a good test of the meter!
I haven't had a lab test in over a year. The last one was before I got a new Cardiologist. :thumbup:

 

[Protimenow]

FWIW, I am NOT convinced that an INR reading of 1.0 on a non-anticoagulated person Guarantees that the imeter is Accurate over the ENTIRE Range of Values. To my mind, it would take 2 or more points of agreement (with some known standard) to guarantee accuracy over the usual recommended ranges (between 2.0 and 4.0)

'AL Capshaw'

Al:

I fullly agree. Such a test wouldn't confirm accuracy, and certainly wouldn't confirm accuracy over a range of values. In fact, if the people who make the meters were concerned about this simple test being used as a verification of accuracy, they might even TWEAK the meters to give non-anticoagulated blood a reading of 1.0. (They probably don't go to the trouble to do this).
Still, a 'normal' value for a non-anticoagulated person is a somewhat comforting indication that the meter is working fairly accurately. (If I took my wife's blood and it showed 0.4 or 2.1, THEN I would be concerned - a .9 - 1.1 probably wouldn't raise any serious questions about accuracy.)
FWIW - even testing against another meter at the same time, and having the same result could possibly just confirm that BOTH meters were EQUALLY wrong. And we've seen how lab tests could be wrong, too.

What's important is that the readings remain fairly consistent, and that we stay within a range we sort of trust. (Beyond that, occasionally validating against a lab I trust, or another probably trustworthy meter doesn't hurt, either). If MY meter, with MY blood, gave me a 1.1 or a 5.0, I'd be concerned, regardless of how accurate I think it is.

 

[Protimenow]

Back soon after I started home testing I didn't believe my INRatio 2 meter, for I tested 7.1. Switched to other hand and tested 6.1. Switched to another batch of test strips and tested 6.8. Then tested my wife that doesn't take warfarin.... her INR was 1.1. :thumbup:

I stopped warfarin for 2 days and 4 days later was back in control.
To me it was a good test of the meter!
I haven't had a lab test in over a year. The last one was before I got a new Cardiologist. :thumbup:

Dayton:
The others on this board suggest NEVER stopping warfarin--and it's obviously somewhat dangerous riding a motorcycle or doing extreme sports with a 6.1, 6.8, 7.1, or whatever your INR REALLY was. The suggestion here would probably have been half doses for a few days until you were back on track. In fact, your experience probably warrants a thread of its own.

HOWEvER - not taking your wafarin for one day, then doing half dose the next day or two would probably have dropped your INR a bit more quickly than half doses for a few days, and may have kept you from too deep a drop three or so days later.

I'm interested in what others would advise (and I really think that your experience could be well handled on another thread).

 

[ShezaGirlie]

FWIW, I am NOT convinced that an INR reading of 1.0 on a non-anticoagulated person Guarantees that the imeter is Accurate over the ENTIRE Range of Values. To my mind, it would take 2 or more points of agreement (with some known standard) to guarantee accuracy over the usual recommended ranges (between 2.0 and 4.0)

'AL Capshaw'

So Al, do you think I should get a lab test? My 'resident 6'5" guinea pig' has always had a .9 or 1.0 reading...hmmmm? Maybe I'll take my machine to my cardio's office next time and compare it with their same type machine - CoaguChek XS.

 

[dick0236]

A couple of years before using the Coaguchek XS meter, I used and INRatio thru Raytel (discontinued the program due to billing issues with Raytel). Once I had a problem with the INRatio INR value being very different from a lab draw when my numbers were "out of range" on the high side, around 5+. A Hemosense tech told me that the numbers, either meter or lab, become less reliable as they get away from the normal values, 2 to 4....and numbers above 5 or 6+ only tell you that the INR is well out of range.

In the past, I am sure I've held a dose for two days before dental procedures. I doubt that I would do that today. If I had an INR above 4.5 today, I would have no problem holding for one day or holding half a dose for a couple days, and testing after 3-4 days.

 

[ALCapshaw2]

Mathematically, a single test point would be considered "a Necessary but NOT Sufficient condition".
A straight line is defined by TWO Points so for a Test System with a Linear Based Reagent, 2 points would be necessary to confirm accuracy over a range. Many of the Finger Stick Instruments use Reagents with an Exponential Characteristic so several test points over the Range of Interest would be needed to confirm accuracy. An Exponential relationship explains why the disparity often increases the higher the reading. My Coumadin Clinic requires a Lab Draw for any Finger Stick INR Reading over 4.5

Switching Gears, AL Lodwick's Dosing Guide for an INR above 5.0 recommends a HOLD and retest in 24-48 hours.
When INR drops to within Theraputic Range, resume dosing at 15-20% below previous weekly dosing level.

'AL Capshaw'

 

[Protimenow]

I use the ProTime meter - though I also use the CoaguChek S as long as I've got strips.
One of the things I like about the ProTime is that the reagent is 1.0. Other meters require a chip that enables the meter to make adjustments for the reagent values on their batch of strips. I've learned that labs have to make adjustments if their reagents aren't 1.0, and the meters do, too, so I'm concluding that having a test system that uses reagents that are different values may introduce the possibility of slight errors. Although the ProTime requires more blood to test, I'll probably stick with (no pun intended) my ProTime - for a few months, at least.

 

[Cris N]

Todd, if I read your post correctly you said there was a difference of 0.5. To be honest, you can fluctuate that much throughout a day (and possibly more). As previous posters have stated you have no idea how accurate the lab test really is. INR is not an exact science!

 

[lance]

My manager will not and never has dropped a full dose for a high INR level.
AND
The change in dose would most likely be for 1 day with a return to the previous dose for the next 6 days. If concerned I would test on Thursday which would be day 4 because I always test on Monday morning.
Both ways work. I'm much more comfortable not dropping a full dose.

 

[olefin]

Dayton:
The others on this board suggest NEVER stopping warfarin--

Hey guy, I'm very well aware of what others are doing. Maybe you should notice when I became a member.

If folks wish to never hold, that is great! I have no problem with what others do.

But I KNOW what works for me.
Over the years I tweaked the dosage when I felt necessary. My cardiologist would always say hold three days when INR over 6.... I would hold for 2 days. Today, I self test and set the dosage.

Even Al Lodwick's Algorithms says the same thing as I do. And most medical professionals recommend the same. I'd never seen Lodwick's Algorithms or The Online Dosage Calculator until I came to this forum.

The Online Dosage Calculator says for INR 4.5 to 5.0...

Decrease dose 10%, hold 0 -2 days, check INR 4 - 8 days

The Online Dosage Calculator says for INR <5.0....

Please Refer to Appropriate Algorithm

I'm interested in what others would advise (and I really think that your experience could be well handled on another thread).

For "your information" I posted my experience to show that I had once doubted my meter. Further more, I will post what I please and where I please. As long as Hank doesn't complain. :thumbup:

Since you have posting what you think I should do....
Well, I think you should make a donation to help pay the bills to support this forum. :wink2:

 

[Protimenow]

Hey, I wasn't personally attacking you. And I wasn't saying what 'I think you should do' And I wasn't telling you NOT to post. I think you're overreacting.

I was just repeating what others here have said. If I was hitting a 5 or 6, I would certainly consider holding a dose, just so my INR dropped a bit more rapidly than it would with a reduced dose.

And, yes, sending Hank a money order or a PayPal payment is DEFINITELY on my agenda.