Fungerpricktest and vein-test and INR-number

I wonder if I am unique with the difference between the fingerprick- test on my CoaguChek XS or on a machine at a hospital and the bloodtest in the vein at the hospitallab? My difference is an INR of 0,8 - 1.2 if I take the two tests within around 3 hours.

There is even a small discrepence (0,1 - 0,4). Otherwise the difference is THE SAME.

This must of course be very important that the patient knows but also the Doctor. Perhaps it only has to do with Lupus Anticoagulant but I am not sure.

I think of all of you out there who wants to selftest and trust what you hear and in fact does not know if the value is reliable. I do not mean the Roche-Machine which you can trust I am sure, but if the INR is to be trusted if it has been done via fingerprint or in the vein. I am most interested to know.

Kerstin in Stockholm

22 Replies

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  • It is known and warned about that people with LA antibodies in particular will have a bigger discrepancy with the machine and prick test and a vein draw. There is normally a small discrepancy which can be allowed for but as long as people with LA know that it is a consistent difference so that they can work out exactly what their reading is then using the machine will still be useful. The machine should be taken to a hospital or GP surgery to be calibrated against one of their machines on a regular basis and at that time you can work out what the difference is.

  • Thanks!

    I was afraid that some members never had doublechequed the two readings a couple of times. That must be very important to do.


  • I think I should mention this to my GP. I was positive for LA but only once (rheumy says it can come and go). I've only ever had my blood tested by finger prick at my GP surgery and no vein draw.

    Feel like I have to tell the Drs everything!

    Thanks for this Kerstin x

  • Hi Kelly,

    Good that you understand what I mean. That was what happened to me also at the very beginning before I started selftesting. A lot of fingerpricktests. As my INR was set very low at that time the difference was not so big. Warfarin meant a lot to me that time even if there was a difference. Now my INR is almost set at 4.0 and the difference is bigger.

    Cross my fingers for you that everything will go your way! It will be ok I am sure. Please let us hear how it goes.


  • I certainly will keep you updated. Thanks Kerstin X

  • My difference was consistently 0.1 for months, then shot up to 1.5 at one test and since then has come down again. Clinic pharmacist says my LA antibodies must have gone up for a short while - not sure if that is right or not. The reading was very obviously wrong - I knew I had not suddenly gone that high.

  • It is also important to do a veintest within just a couple of hours and that the lab sends the blood-test away very fast (I can of course not explain this as am I not medical trained). Do you use a CoaguChek XS from Roche?

    As you say you have double-chequed a lot of times, only once could eventually be something wrong done from the lab . I do not know just guess. I always test at my Hospital-lab.

    Very good as you are LA that the discrepence is so small. Do you have all the antibodies positive and in high titres every time as I have?


  • So far I test only at the hospital clinics - but they use CoaguChek (not XS, their machines have barcode readers and are networked I think, but the testing bit is the same).

    When I have been crosschecked the venous samples were done at the same time (within minutes).

    I am only positive for LA and only at low levels (although it cannot be tested now).

  • Good for you!


  • Self monitor machines do not give accurate readings for patients wth APS

  • Hi WandaE,

    Could you please explain your experience with the machine and what you have learnt about not accurate readings with it.

    Very interested to hear from you!

    Best wishes from Kerstin in Stockholm

  • I do both coaguchek and vein draw. Usually within an hour of each other. I am LA positive too. The majority of time the laboratory is lower than the home test. I've have a few of the results the same but the differences range between 0.1 to 0.4. Usually the higher my INR, the higher the difference. I have enough data between machine and lab to rely on the machine when I don't have access to lab on occasion such as when on vacation.

  • Hi Mylafont!

    I am trippel-positive with high titres for 14 years now. Yes, I also rely on the machine which means a lot. My difference is also bigger with a high INR and the machine-INR higher than in the vein at the hospital-lab like you.

    I wonder what your therapeutic range is? I have been selftesting 4 years now and I notice that I need a rather high INR. My level is now set to an INR of 3.2 - 3.8 and I definitely feel better near 4.0. I selftest every second day.

    The doctors said some years ago that my symptoms were "neurological" but now they have found that I have pulmonary hypertension and leaking heartvalves. So "brain"-APS does not excist according to me and what i have learned. Hope your B-12 was ok. Exercise and to keep the bloodpressure normal is important with this illness.

    Best wishes and thank you for answer my question.

  • My INR range is 3-3.5. I am working on getting the clinic to raise it to 3-4. I feel better when it's higher and clinic is always changing my dose each week when it's not in range. I figure if my range was broader there'd be less changing.

    Not sure what you mean by no 'brain' APS. It is the form of APS that I have in that it only affects the small veins in my brain and not the larger ones in my legs, heart and lungs. I do see a stroke neurologist along with my rheumatologist.

    Seems confusing because you would think it's a blood disorder so it would affect you all over. I've been told by my doctor that it's rare even among APS patients.

    There is one other member here that is following me that was told she has it only in the brain too.

    I feel blessed don't have to fear the PEs or DVTs or heart clots, but I have had many TIAs and I have seizures. So in addition to warfarin and plaquenil, I also take Topamax twice per day.

  • Difficult questions. Remember clots are moving!

    I have read many of Prof Hughes books about APS as I want to understand what is happening in my body in a way to have a sort of control. I have learnt a lot from this Forum also.

    We have learnt that the Neurologist do not "get" what APS is - too thick blood that has to be properly thinned to avoid more clots and microembolies.We do not bleed from it but clot.

    Important to have a Specialist who really knows what APS is and I think you must work on that Specialist rather than on the clinic to have your INR raised . I practically never change my tablets but instead look at my exercise, new extra drugs, green vegs, ev alcohol as these things change the INR for me. I make personal notes each day to know and remember these things.

    We are all different; some are primary APS, others have other autoimmun illnesses. Some have only one antibody, others 3 antibodies positive. Some have low titres others have high titres.

    What do you mean with "it is rare even among APS patients"?


  • List of APS specialist in NJ, USA? Thank you in advancešŸ¤”

  • Wittycjt,

    I have learnt

    Kerstin in Sweden

  • Tried, not successful, thanks though

  • I don't have any symptoms and my INR is usually between 2 & 3... What symptoms do you people have?

  • Hi Wittycjt,

    With your past history (also relatives) and a diagnose of APS you should be on anticoagulation.

    I wonder if you have read "Sticky Blood Explained" by Kay Thackray? Do that if not.

    I have read that you selftest. I hope your Specialist have doublechequed the fingerpricktst with the veintest at a lab within 4 hours time.

    Please read what I have written earlier on this question from me. I have Pulmonary Hypertension because I was without any bloodthinner for several years and I have microclots and you do not always "feel" them. I also had exstremely high bloodpressure.

    If you go around with an INR of 2.0 I shoud say that you are not anticoagulated enough for this illness (APS)! "Normaly people" without APS may have that range when on Warfarin. We do not bleed from APS but clot! Most of us feel best at an INR around 3.5 - 4.0 or even higher.

    It is exstremely important to be anticoagulated with this illness and also to have a Doctor who really knows how to treat you!

    I am afraid you just have to put a new question on here and ask members for a Specialist as I am from Sweden and do not know of all the "rules".

    Best wishes from Kerstin

  • I am on anti coags

  • What sort of anticoagulation? If you are on Warfarin your INR must be within the stipulated range decided by your Consultant or Specialist. What is your therapeutic range? Mine is an INR of 3.2 - 3.8. I also selftest quite often.


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