I am a gadget person, using alivecor and coaguchek to keep tabs on my AF. I am not obsessive and rarely use alivecor unless I feel a different beat and like to know I can record it (probably about once a month).

Last night I was doing my fortnightly INR check and it was 4. This is very high for me and as the drop of blood I used was tiny I decided to repeat the test. So another finger and a good stab (ow) produced a good big drop of blood and this time INR 2.5.

Now, was the first sample too small or is machine faulty?? Any ideas??

Thanks in advance.


18 Replies

  • I don't use one myself but the surgery does and sometimes throws a fault code. If my hands are not dry after washing (always insisted upon) it can give a higher reading and if the sample isn't sucked into the strip properly it faults. I wouldn't worry too much personally if the good sample gave a good reading.

  • Sure it wasn't error 4 that showed up first ? It shows up on my machine when there's not enough blood. Terry

  • Thaks for reply Terry but no its not a fault code. I too get them from time to time so would recognise this.

  • Hi Marie

    I like gadgets as well and they are both ,for the most part very good.I had a problem with my Coaguchek machine I started to get several higher readings than the surgery and then went up to 5.9 when I knew I was only 2.2. Although Coaguchek said that the machine does not become faulty they did replace it and I haven't had any problems since ,so who knows-my guess is that something can be faulty-either the test strips or the machine.If you have a problem again get in touch with Roche for a replacement. I'll be interested to know how you get on.Good luck


  • Certainly comes in handy for me - Diagnoste, checks both Blood Pressure and Heart Rate. So when I feel "off - AF", certainly can and does confirm, plus lets me know twofold to slow down.


  • I once repeated a test as realised my finger was wet and got a very different reading

    ? relevant?

  • Thanks for replies - helpful, as always. I have reported this to Roche and will see what they say.

    Hands definitely dry.

    Probably just a glitch due to small blood sample.

    Will keep an eye on it.

  • My machine does not do a reading if there is too little blood and gives an error warning. Mine has a comparison check at the clinic every 6 months. You could try new batteries even if not yet indicated on screen. I think I would do a third test so you know which one is right

  • Yes, I agree, I have used too little blood in the past and was given an error code but no inr reading. This time, no error code but a high reading. I will look at batteries.


  • I once had a very high reading. I realised I hadn't washed my hands and had just rubbed magnesium oil in. I washed my hands and then tested again twice and the reading was back down to 2.7. I always wash my hands first now. That is however the only time that has happened in 3 years apart from the error codes I sometimes get. If I ever have an unusually low or high reading I would always check it again and/ or with the clinic. X

  • Thanks but had no it rubbed in magnesium oil. Apart from error codes this is the only time I have had this happen. Hope just borderline blood sample but will be aware.

    Thanks for reply

  • If you read your instruction leaflet for the Coaguchek you will find a bit on how to clean the part of machine that takes in the loaded strips, suggest you give it a go!

  • Yes, that's an idea, thanks.

  • Not at all, hope it works!

  • Can someone tell me what Alivecor is please????

  • Alivecor is a device that you use with an android phone to take an ECG whenever you want to. You download a free app to your phone that allows you to see the ECG strip on your computer (and to print it if you want) as well as on the screen of your phone. If you use it as recommended it is the same as a number 1 lead on an ECG.

    More info here:

  • Hi philologus

    I fôllowed your link and was really interested in buying one of these but someone had asked if it could be used with a moto e or g and the answer had been removed so am very wary of buying. Have you heard of anyone using one of these with a Motorola? My cardioversion nurse had me use a two day monitor when I told her I had odd fast heartbeat runs in the evening sometimes but of course nothing happened when I was wearing it......

    Regards, Cleocat

  • I use mine on a Samsung S3 and it works well.

    It was thought that I had A-fib but none of the readings I got showed that to be the case so it was then decided that I had heart failure caused by a very high number of ectopic beats. The Alivecor backed this up. I started taking magnesium and the ectopics stopped but then came back when my dosage of a diuretic was doubled to get rid of fluids. I am considering stopping the diuretic when I see the nurse at the HF clinic on the 13th of this month. In the meantime I am doubling my dose of magnesium and checking what happens with the Alivecor.

    The good thing about the device is that you can use it as soon as you start getting symptoms and then show your Dr a 30 second ECG print out.

    You can also learn how to interpret your results here:-

    You can ask questions about compatibility with your phone here:-

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