That first test is a massive difference. Personally, I have mine checked with an anticoag machine at the GP surgery. My heamo has me get a pairing test done every 8 weeks (doesn't believe the coag machines are as accurate as obviously the machines need to be calibrated regularly and sometimes the strips can be faulty) and there is always a difference of anything up to 1.0, but nothing as wild as yours. The ones from your vein are actually supposed to be more accurate but obviously mistakes can happen with the tubes, & whoever is testing the blood in the lab etc (have personally never had this). How very scary for you.
I read you are only positive to one of the 3 antibodies they test for a diagnose of APS. That is Lupus Anticoagulant (LA). Is that correct?
I live in Sweden and am triple positive incl LA but know they say that we who are positive to LA may have big difficulties to use the CoaguChek XS.
I had to stop using that machine as the difference within 2 hours time between the vein and the fingerprick test could be over 1.5 some times. The vein usually was the lower result. A high INR usually gives a bigger difference between the two.
I use iLine microsystems and with that machine there is only a difference between the vein and finger with 0,2 perhaps. That is quite ok as to my Hematologist who is responsible for my using Warfarin with an INR between 3.5 - 4.0. I hope you are at an INR that suites your symptoms.
But I do veintest very seldom nowadays as I selftest at home several times a week and now I have parallell tested several times before so I only test at the hospital lab as I take other bloods seeing my Hematologist or Rheumatologist or when I want to test extra. 2-3 months between the vein tests.
I do not know if this has helped you at all but it can be interesting for you and also others read what we say here. LA is a trouble obviously.
I am glad you are doing INR clinic and also your machine to show up the discrepancies, I hope you and they manage to get to the bottom of it all, with all this monitoring going on. Let us know the outcome, MaryF
The hospital I used to attend used a finger prick test and once told me to wash my hands before test with alcohol gel needless to say my Inr result was sky high . When I pointed out it would be the alcohol gel residue she performed a new test and result was back to normal . I have 2 self testing machines and calibrate them against each other and I have to say they are very accurate . Moral of the story is hospitals are not perfect Trust yourself and your own equipment and after a long time of using warrfarin you pick up little signs from you body and can tell when one is high
interesting - at the hospital I go to for comparison/review testing they have a big notice on the warfarin clinic doors saying "DO NOT wash hands with the gels/sanitisers" before your test, and that if you have done you will have to wash again with soap and water before test and that they will assist you doing this. Not sure if that last bit is a helpful offer or a threat... but on the first part they are very very clear - do not.
I wonder if you have tested in the vein? That result should be the the correct one.
When I first started Warfarin the Doctor (not in a hospital) used a fingerprick machine. As there is a difference between the vein and the fingerprick it was not the correct result but nobody knew at that time who APS works (the Doctor was not a Specialist at the GP and thought it was the value I had) . Therefore my REAL INR was lower and I had microclots again. We must parallell test several times and do it within not more than 2 hours time to be able to trust the result. I am positive to Lupus Anticoagulant and triple positive. We are very sensitive to INR going up and down a lot.
when I was first diagnosed with aps I had my first few Inr tests at the doctors surgery in Scotland where I used to live and they took from my vein but ever since I have attended a clinic in England where I moved to shortly after diagnosis and they just do finger prick tests eventually I just bought a couple of home test machines and I rarely attend the clinic nowadays
You do not have to parallell test fingerprick tests but a fingerprick test with a vein test should be done as I have said there can be a rather big difference between the two tests and it is always the vein test that is the correct one if you use a lab that is ok of course.
This is weird, I agree with you. In 20 years of taking warfarin and being on support groups etc I have never come across venous tests being inaccurate while finger prick testing is ok. Some people can’t stabilise on warfarin so their venous tests go all over the place unexpectedly. So I’m wondering if this is causing the problem with your venous tests, I doubt it because you are quickly back in sync with your home testing but interesting therefore that your finger prick tests are ok.
As there is this known problem, then get them to prioritise your 2nd venous test result so that you do not get dosed on just the first one. That’s about all I can suggest. Interesting problem but it must be very worrying and frustrating for you.
either they are using the wrong vile/tube to collect, or they are not mixing it immediately upon collection, or they are letting the vile sit too long before testing. It happened to me once and the nurse used the wrong tube was the result.
Yes... but... such error has now happened twice recently with same patient (see original posters similar story from a month ago).
IF (big if) there are several other errors with other patients at same hospital/lab then it might just be coincidence / bad luck, otherwise I'd say it is extremely unlikely to be a random error. If the reported errors in the same place/timeframe are all with this patient then something specific to the patient is very likely the cause. What, I don't know. Fingerprick tests usually read higher if there is a difference, venous being (much) higher is very very odd before you even get to two such incidents with same patient in short time.
Hi Kevin that has happened to me as well! Venous Inr is classed as the “gold standard” but I’ve had false high results and low before..
I was told to stop warfarin but ended up in hospital with TIA’s. I challenge the decision to stop as felt clinically well and asked could the result be wrong it was 7.8! Plus I was told never stop always titrate.. My target is 3.5 and I self monitor now.! But back then it was not advocated or common to do so! Then not that long ago I was told my venous sample was 2.8 to increase my warfarin but I explained I felt well my Coagu Chek was 3.4 so refused to. The tourniquet was particularly tight over the vein so suggested that might have interfered with the results as I believe happens in the opposite way when bloods are left in natural heat ( sunlight) as had 3.6 results when in a&e with symptoms of dvt machine was 2.4. Coagu Chek next day was correct as correlated with venous sample at 2.5!
I’m glad you posted I thought it was just me thinking this! Kath
Please give us an update if you find out what the problem is. I'm in the US where home testing with a CoaguChek is not as common. But once I found out the CoaguChek was 0.0 to 0.7 lower than my venous INR, I was switched to venous only. So, I do venous tests once a week to monitor my INR. I'm fairly stable, so I've never been concerned the venous draw was inaccurate. Now I'm worried because I don't have a secondary method to compare and check it with. I'm only positive in the IgM antibody, so I'm not typically supposed to have a problem with CoaguChek.
At my yearly hematology follow up, I've recently had them check my chromogenic factor X to check that the venous INR is accurate. It has been, though this year it has slipped a bit but is still fine. Yet, because labs can differ in what machines and assays they use, it's a little questionable how helpful it may be as my weekly testing is done at a different clinic and lab.
As for your situation, depending on the size of the hospital you go to or the lab system they use, it's possible the difference is an inaccuracy or difference between machines or testing methods/assays and how they interact with your blood. However, as others have suggested and seems far more likely, it could be an error in the drawing process itself (wrong tube, not filled all the way, etc.). I think it'd be worth it to follow up with the hospital or the nurses/phlebotamists doing the draw on what the error is so you can know and keep an eye out.
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but on the first part they are very very clear - do not.
Different INR readings from Finger pick and lab. 
Coagucheck self test strips 
Episodes of vision loss...
venous blood draws vs finger stick
November INR Chart: 
