INR Lab vs Office Machine & Thalassemia

[Arc_Weld]

Hi Everyone, Michael here:

I am confused.
I just had a new St. Jude's ARV installed on 10/6/05.
I am on Coumadin.

I have a blood disorder called Thalassemia Minor.
My red blood cells are really really small.
My H&H is always border line low... anemic.

Anyhow, everytime I get my finger stuck and my INR checked....
Its VERY VERY high...8+, 8+, and 5.3.......
but after sending my blood to the lab...
its always ok...3.0 to 3.2

Does anyone else have this issue? or I am just the exception to the rule.
I am guessing that Thalassemia flakes the office testing machine out.

 

[geebee]

Well, recently there was a recall of some testing materials used in labs because it was causing errors in INR readings. So, my question would be, is how do we know the lab test is correct and the finger stick wrong?
I always get a lower result with lab sticks over my INRatio monitor but it is only about .4 to .6 difference.
I would try to find out whether the lab you use was using the recalled materials. There was a thread started recently by Al about the recall. You should look for it under Al's threads for more info.

 

[Guest]

I suspect that you correct and you are not a good candidate for fingersticks. They are dependent upon the blood flowing up a tube. With thalassemia your blood runs up the tube too fast. The INR is determined by how far the blood flows in a given amount of time. The tests done in hospital labs do not depend on flowing up a tube. Therefore, thalassemia does not throw them off.

 

[Luana]

I have a blood disorder called Thalassemia Minor.
My red blood cells are really really small.
My H&H is always border line low... anemic.

Anyhow, everytime I get my finger stuck and my INR checked....
Its VERY VERY high...8+, 8+, and 5.3.......
but after sending my blood to the lab...
its always ok...3.0 to 3.2

Does anyone else have this issue? or I am just the exception to the rule.
I am guessing that Thalassemia flakes the office testing machine out.

I had the opposite happen almost 2 years ago after AVR. Readings at home with testing unit were in normal range, but a lab draw was much higher. I have beta thalassemia, minor.

I know someone else brought this up about a month ago, but haven't seen any additional posts. I've contaced Phillips INR about it, but no response.

This is an old thread, but just thought I'd post in case anyone has updated info and can point me in that direction.

 

[pem]

Hi. I have Thalassemia Minor. I ran a small study on myself and found that the at home readings (conducted by home nurses) were sufficiently inconsistent with the lab readings that I had to stick to the lab. However, the readings were off in both directions IIRC, and the time it was most off, the at home test indicated a lower level than the lab test. I have since learned that there are a number of sources of variability. I concluded that the reason the lab and at-home results were inconsistent is: 1) different nurses each time pricked my finger; 2) some waited for the alcohol to dry and some didn't (this can affect viscosity and capillary action I believe); 3) they all used the same brand home-test machine, but each one had their own machine, so perhaps the machines were not properly calibrated to each other.

In sum, I have seen no evidence so far to suggest that at-home vs lab results are different due to Thalassemia. But, the jury is still out. I intend to get an at home kit, which I will use in parallel with the lab tests until I am convinced one way or the other that they are sufficiently in line with each other.

Another possible confound I should mention is that, in principle, when they draw blood for a lab test for INR, they are supposed to draw two vials and throw away the first one. I have found that in practice, that only happens about half the time. So if results are reliant on doing it that way, that would also explain some variability that I've seen.

Hope this helps. I'll continue to post my findings in this comparative study once I get my home test kit.

Thanks,
pem

 

[Luana]

Hi. I have Thalassemia Minor. I ran a small study on myself and found that the at home readings (conducted by home nurses) were sufficiently inconsistent with the lab readings that I had to stick to the lab. However, the readings were off in both directions IIRC, and the time it was most off, the at home test indicated a lower level than the lab test. I have since learned that there are a number of sources of variability. I concluded that the reason the lab and at-home results were inconsistent is: 1) different nurses each time pricked my finger; 2) some waited for the alcohol to dry and some didn't (this can affect viscosity and capillary action I believe); 3) they all used the same brand home-test machine, but each one had their own machine, so perhaps the machines were not properly calibrated to each other.

In sum, I have seen no evidence so far to suggest that at-home vs lab results are different due to Thalassemia. But, the jury is still out. I intend to get an at home kit, which I will use in parallel with the lab tests until I am convinced one way or the other that they are sufficiently in line with each other.

Another possible confound I should mention is that, in principle, when they draw blood for a lab test for INR, they are supposed to draw two vials and throw away the first one. I have found that in practice, that only happens about half the time. So if results are reliant on doing it that way, that would also explain some variability that I've seen.

Hope this helps. I'll continue to post my findings in this comparative study once I get my home test kit.

Thanks,
pem

1) What is IIRC?
2) Different nurses pricking should not yield different results.
3) Have been going to the lab almost 2 years now for INR draws. I've never had 2 vials filled.

I'm looking for reliable information from one of the manufacturers of these machines about this, and I've not received any type of response from the posts I've submitted about this concern. I would think they might be able to give me some information, but apparently not. Anecdotal evidence is not something I can rely on. I see no sense in having a home unit and supplementing it with lab draws.

 

[Protimenow]

There may be some variance from person running the test to person running the test - your comment about alcohol drying (or not) may inject some error, and if the 'nurse' milks your finger (or not) to get the blood, the results may vary. Also, if it takes more than 15 seconds to get the blood onto the strip, there may also be some variations. In short -- if you had your OWN meter, and ran the tests the same way each time (by yourself), the variables introduced by poorly trained/marginally competent 'nurses' could be avoided. Depending on the meter being used (these were ALL made for clinical use, although some are also being sold for home use, too), you will probably have to get the drop onto the strip within fifteen seconds of incising your finger and will have to use your FIRST drop of blood to get an accurate reading. (The ProTime meters don't use the first drop, but probably aren't being used as much as InRatio or CoaguChek XS).

Personally, I'm using an InRatio, and don't use alcohol on my finger before incising it. I rinse my hand under warm water, getting more capillary blood into the fingertip. I've had no problems with finger infections in the few years that I've been self-testing - and am not convinced that alcohol is really necessary before running the test.

I don't know if thalessemia effects the INR in either meter, or has an impact on lab results. FWIW -- there's processing of blood done by labs that could also introduce some variance in the results. You may want to google for an answer (i.e: thalessemia and INR, or thalessemia and InRatio, or thalessemia and CoaguChek, or similar terms)

 

[pem]

1) What is IIRC?
2) Different nurses pricking should not yield different results.
3) Have been going to the lab almost 2 years now for INR draws. I've never had 2 vials filled.

I'm looking for reliable information from one of the manufacturers of these machines about this, and I've not received any type of response from the posts I've submitted about this concern. I would think they might be able to give me some information, but apparently not. Anecdotal evidence is not something I can rely on. I see no sense in having a home unit and supplementing it with lab draws.

IIRC = "If I recall correctly"

I do not intend to have a home unit AND do lab testing forever. The idea will be to get a home unit and test at the lab in parallel until I am either convinced that they produce roughly consistent results or that I can't rely on one of them.

It must be frustrating to not get proper feedback on this topic. Sorry I can only provide anecdotal evidence for now. Eventually I hope to have better hard data from a case study of 1.

Best,
pem

 

[pem]

Thanks, Protimenow, that is very helpful on several counts. I like the idea of washing with warm water and soap instead of using alcohol. It seem less likely to affect the results. I'm not surprised that there are processing-based effects that occur in the labs as well. I like the idea of home testing because although it doesn't completely remove human error, it reduces the number of humans in the pipeline

THanks again,
pem

 

[Protimenow]

Pem - you're welcome.
Personally, I wouldn't do both lab and home testing. I would trust my meter. The main reason for lab testing is to confirm an unexpected reading. (For example, if your meter tells you that your INR is 4.5, it's accepted practice to confirm this with a lab test - and to be careful until you get confirmation). If your INRs are consistently within range, I would trust the meter. (Assuming that lab results may be +/- .2 or .3, does it really matter what the lab reading is if the variance from your meter's results keep you within range?

Regardless of the meter you're using (with the exception of the discontinued CoaguChek S), the strips include built-in quality controls. If your meter shows a QC error, THEN you should consider trying another strip and possibly getting a lab test. Otherwise, I usually trust my meter. (A few months ago, my meter gave me a 1.1 -- I repeated the test, tested using a different meter - and confirmed that the problem was with my INR, and not an error from meter and strips)

 

[Luana]

I don't know if thalessemia effects the INR in either meter, or has an impact on lab results. FWIW -- there's processing of blood done by labs that could also introduce some variance in the results. You may want to google for an answer (i.e: thalessemia and INR, or thalessemia and InRatio, or thalessemia and CoaguChek, or similar terms)

If you scroll up to post #3 from Al Lodwick, there is a difference in the process in how the blood is tested in a home unit vs a venous draw. I don't know if there's anyone as knowledgeable as Al Lodwick when it comes to INR and testing, and, yes, I've tried googling it, can't find anything.

 

[pem]

Pem - you're welcome.
Personally, I wouldn't do both lab and home testing. I would trust my meter. The main reason for lab testing is to confirm an unexpected reading. (For example, if your meter tells you that your INR is 4.5, it's accepted practice to confirm this with a lab test - and to be careful until you get confirmation). If your INRs are consistently within range, I would trust the meter. (Assuming that lab results may be +/- .2 or .3, does it really matter what the lab reading is if the variance from your meter's results keep you within range?

Regardless of the meter you're using (with the exception of the discontinued CoaguChek S), the strips include built-in quality controls. If your meter shows a QC error, THEN you should consider trying another strip and possibly getting a lab test. Otherwise, I usually trust my meter. (A few months ago, my meter gave me a 1.1 -- I repeated the test, tested using a different meter - and confirmed that the problem was with my INR, and not an error from meter and strips)

I see your point. I think for my own peace of mind (in part because I have Thalassemia Minor, and in part because I had very different results between the two tests when they were done in parallel by the home nurses), I want to see that with regularity, the lab and home test results are comparable. Or perhaps I will find there is an offset such that the lab result is always (reliably) x lower than the home test, such that when I move to only using the home test, I can apply that adjustment to my readings to get the "lab equivalent". I realize there will be some measurement error in both the lab tests and the home tests, so my expectations are tempered, but, again, before I rely on the home test I will conduct my little study If I didn't have Thalassemia, I probably wouldn't worry about it.

I didn't realize about the build in QC - that will help I'm sure. Thanks for pointing that out.

pem

 

[pem]

If you scroll up to post #3 from Al Lodwick, there is a difference in the process in how the blood is tested in a home unit vs a venous draw. I don't know if there's anyone as knowledgeable as Al Lodwick when it comes to INR and testing, and, yes, I've tried googling it, can't find anything.

I would love to contact Al directly. His site appears to be down. Does anyone have an email address for him?

It is difficult to reconcile what he wrote about Thalassemia blood and INR in that most of my parallel tests (lab vs home) produced equivalent results.

Thanks,
pem

 

[Protimenow]

AL's post was written in 2005. I don't thnk that his claim about the meters relying on blood flowing 'up a tube' is necessarily accurate with the current meters. I believe that both the InRatio and the CoaguChek XS don't try to make the blood 'move' in a tube, once the capilary action inside the strip draws the blood inside the strip. From there, reagents react with the blood, and there's a change in electrical resistance (or something) that the meters detect, that correlates with the blood clotting. Although I haven't checked the Roche or Alere sites to get an answer to the Thalessemia question, I'm not sure that Al's post is relevant to the newer meters.

 

[Luana]

AL's post was written in 2005. I don't thnk that his claim about the meters relying on blood flowing 'up a tube' is necessarily accurate with the current meters. I believe that both the InRatio and the CoaguChek XS don't try to make the blood 'move' in a tube, once the capilary action inside the strip draws the blood inside the strip. From there, reagents react with the blood, and there's a change in electrical resistance (or something) that the meters detect, that correlates with the blood clotting. Although I haven't checked the Roche or Alere sites to get an answer to the Thalessemia question, I'm not sure that Al's post is relevant to the newer meters.

Yes, I know it was written in 2005; the post is clearly dated. Because of the years gone by since then, I've been trying to get info from meter companies, which I've stated in my previous posts here, yet none of the companies have responded. One would think even though this is not a common question, I would have gotten a response from posts that go back 5-6 weeks.

Protime, please read what I've written if you're going to post a response to me. I feel like I have to repeat info to what you post, so it doesn't appear you're reading, just tossing a response out for the heck of it. I am looking for answers, and if you don't have any, that's fine.

 

[Protimenow]

Luana:

I read your post. I read what you've written. And if Al's post wasn't clearly dated, I wouldn't have been able to bring up the date. I wasn't attacking your post.

I was just stating that what Al posted may not be relevant to the current set of meters. (The InRatio, for example, uses an electrochemical process -- the blood mixes with reagents, and the impedance (resistance) changes when the blood clots. The meter detects the changes and calculates the INR and Prothrombin time based on the change in impedance. This sure doesn't sound like blood flowing 'up a tube.') I also addressed Al's comments about blood going 'up a tube' -- which should indicate that I actually READ both YOUR post, and Al's. The method of action between INR meters and lab testing may still be different, but 'up a tube' probably doesn't apply and BOTH METHODs require on a reagent that causes the blood to clot. The method of testing the speed of clotting, in response to those reagents may differ -- but lab and meter testing is based on similar approaches.

Also -- I wasn't responding to you - nor was I attacking you. And, FWIW - wouldn't your personal complaint have been more appropriate as a private message?

I've checked the InRatio/Alere site and materials, and haven't found a direct reference to thalessemia major or minor. I've sent a query to Alere's InRatio support and will post any response.

I don't know about Roche. I haven't asked them, nor have I looked into how their meters determine prothrombin times.

I suspect, though, that if this forum doesn't have an easy answer, perhaps contacting the meter manufacturer and asking directly should get an accurate answer.

 

[pem]

I am looking for answers, and if you don't have any, that's fine.

Hi Luana,

I understand your frustration about not being able to get this information. I share it. But I think protime is trying to help. In fact, her post is thought-provoking. I will try to develop a better understanding of how these test devices work and the possible implications of Thalassemia. My intuition tells me that protime is right in that there is probably little to no effect. But I will attack the issue from two directions: 1) seeking information about the machines, how they work, etc, and 2) conducting my own personal study of parallel readings between the home machine and the lab. As I have Thalassemia Minor, if I get many successive readings that are the same between home and lab, I will feel confident about the home machine. I will post my findings on this site.

Self-advocacy can be frustrating, I know. I think this site and the folks on it are respite from that frustration. I think the common agenda is better health, longevity, and quality of life. Even if we have different opinions or approaches to things, I think this commonality binds us as heart valve patients and as humans. For this reason, I try to appreciate all of the posts - even the ones that might push my buttons

Best,
pem

 

[Protimenow]

Well said, Pem (even if you got my gender wrong). We're all in this for probably the same reasons.

In the 'professionals' area of the sites for InRatio, ProTime, and probably also Roche, there are links to scholarly articles comparing machine testing and lab testing. The reports show all machines to be very closely correlated to the lab results -- and if you use a machine consistently, you'll be able to tell when your INR spikes or drops to a degree you didn't expect. Such a deviation from your 'normal' range should prompt lab verification. In most cases, if you're on top of diet, activity and dosing, your values should be fairly consistent --deviation from such scores, again, will prompt confirmation by lab blood draw (and possible dosage adjustment or other intervention).

There are also reports that conclude that those who do their own testing stay in range more of the time than do those who have to go to labs for testing.

 

[pem]

Well said, Pem (even if you got my gender wrong). We're all in this for probably the same reasons.

What can I say - it was 50-50 ;-)

 

[ElectLive]

I don't have answers, nor direct experience, but thought I'd offer some suggestions for further inquiry, based on my own long history with other medical devices. First, perhaps someone has already done this, but I didn't see it mentioned: the accompanying literature (product guides and package inserts for things like test strips - this may even be online) generally without fail include contraindications and limitations of use. It may not specifically address thalassemia but perhaps it will indirectly (anemia, hematocrit, etc). Now, this will still likely be generalized and not definitive for any given patient. But in my experience, companies that make medical devices will research and do almost anything you need when you give them a call and tell them you are considering acquiring their device, but have an issue that needs to be addressed. For one device of mine, a company was unable to address my concern through research to my satisfaction, but offered me a training "loaner" device so that I could verify it would meet my needs. It did and only then did I commit to purchase. I've dealt with different companies, sure, so could be wrong in this instance, but might be worth a shot...