Conclusions From Self Testing My INR Daily
Tomorrow, it will be eleven weeks since I started self testing my INR on a daily basis. The results are here.
I should say that after I had my stroke, an eminent cardiologist said that if I got my Warfarin right, I wouldn’t have another stroke.
So can I come to any conclusions from the tests I have been taking?
I did miss one day early on, but otherwise I’ve taken the test successfully on a daily basis.
I’ve now developed a daily routine in the morning, where I do my stretching and exercises after checking my computer, then have a shower and breakfast, before doing the washing-up by hand, which warms my hands. I then take the test and only rarely do I fail first time and need a second strip.
So the first conclusion, is develop a routine for when you do your tests, that suits your personality and lifestyle.
One thing that you notice from the tests, is that there is quite a large variation between days. A change of 0.5 in the INR, either up or down is not uncommon. This is not a problem, but it could with some people worry them and then they might start to chase their target INR, by constantly changing the dose.
Hot days incidentally, do seem to try to force the INR upwards and although you won’t find this on the Internet, a medical professional has told me that it happens.
I use a very simple manual algorithm, based on my training and experience as a Control Engineer. I know from when I was living in Suffolk, that a Warfarin level of 4 mg. a day is about right to meet my target of 2.5. So I use a simple algorithm, summarised as follows.
INR less than or equal to 2.2, take 5 mg.
INR higher than or equal to 2.8, take 3 mg.
INR between 2.2 and 2,8, take 4 mg.
So how has my INR behaved?
If I look at the average value of the last 28 days, it is 2.56 and this rolling 28 day average has been within 0.1 of 2.5 for the last seven weeks. I couldn’t calculate it before, as I didn’t have enough data. An interesting figure is that the standard deviation of the readings is about 0.3. Effectively this says that nearly all of the readings are within 2.2 and 2.8, which is within my target range of between 2 and 3.
So as the patient, I think I could safely say that my simple algorithm works.
But perhaps what is most interesting is that the 28 day average for the dose I’m taking is around 3.8 mg. So rounding this to the nearest tablets, that means if I can’t take a reading for some reason, then I should take 4 mg.
So I can conclude that the daily testing has given me a very sensible daily dose, which is virtually the same, as I took, when the tests were done by nurses, hospitals and laboratories, at great expense to the NHS.
So should all those going on Warfarin be assessed to see, if they could self-test their INR levels?
I believe they should! And it’s not just me!
An organisation called the Anticoagulation Self-Monitoring Alliance is pushing for more self testing. Be cynical if you like, but it is part-funded by Roche, who make the self testing meters.
On the other hand, how many diabetics test their blood sugar levels regularly and have a better lifestyle because of it?
Did The Hot Weather Cause A Jump In My INR?
The last few readings of my INR have been.
Monday, July 8th – 3.2
Sunday, July 7th – 2.3
Saturday, July 6th – 2.4
Friday, July 5th – 2.6
Thursday, July 4th – 2.3
Wednesday, July 3rd – 2.2
Tesday, July 2nd – 2.5
Monday, July 1st – 2.8
Sunday, June 30th – 2.6
Saturday, June 29th – 2.6
I don’t think anybody would complain at those figures, as I’m supposed to keep the INR between 2 and 3, with a target value of 2.5.
I know from past experience, that in the summer, my Warfarin level is around 4 mg. a day. So generally, I take this amount every day, but if the INR is 2.8 or over, I take 3 mg. and if it is 2.2 or under I take 5 mg. It is a classic simple algorithm of the type I learned at Liverpool University in my degree in Control Engineering.
But notice how today, after the very hot and sunny day yesterday, my INR rose sharply. I shall be watching the figures intently.
Testing My INR On A Hot Day
The temperature in my house is 29.1 °C and as I had one test strip left in the current batch, I used it to test my INR,this afternoon when I came in from the heat outside.
The value was 2.3, which is only a little bit lower than the 2.6, it was this morning, when I took my daily check, the values of which are here.
Obviously, one test doesn’t give a conclusive result, but despite the heat, my INR has probably only changed within the limits of experimental error.
My Health Goes Up And Down
This has been a rather up and down week for how I feel.
On Monday, I had an echo-cardiogram and I think it went pretty well. At least I was told it was better than the last one.
But then yesterday, I went to Brighton for lunch and coming back, the weather had broken and I was choking and wheezing, like I did as a child.
I was feeling bad in the the evening and I texted a friend, who has suffered similarly this winter. She texted back “Not cough but catarrh and intermittent headache.”
That could sum me up too and in some funny ways, I’m almost worse indoors.
I’m looking at how all this relates to my INR, which I’m now taking daily.
At least my INR is within its prescribed range and for the last few days it has been spot on 2.5, as measured by my CoaguChek device.
Just going to have a bath and put my head under the water. Temporarily I should add!
The Sun And INR
For the past couple of weeks, I’ve been testing my INR daily. These are the early results taken daily on my Coagucheck.
Tuesday, June 4th – 3.0
Monday, June 3rd – 2.9
Sunday, June 2nd – 2.8
Saturday, June 1st – 3.0
Friday, May 31st – 2.9
Thursday, May 30th – 2.3
Wednesday, May 29th – 2.7
Tuesday, May 28th – 2.5
Monday, May 27th – 2.4
Sunday, May 26th – 2.2
Saturday, May 25th – 2.2
Thursday, May 23rd – 2.4
Wednesday, May 22nd – 2.2
Tuesday, May 21st – 2.2
Monday, May 20th – 2.1
Sunday, May 19th – 2.5
Saturday, May 18th – 2.3
I’m not having any medical problems, but to a certain extent I’m scientifically curious, and feel that the INR swings up and down a bit. As I’m paying for the strips, no-one can say, I’m wasting NHS money. A cardiologist once said to me, that if I got my INR right, I wouldn’t have another stroke.
I have to keep my INR between 2 and 3, with a target value of 2.5. As I’m a trained Control Engineer, I’m using a simple algorithm to make sure I’m in range and to try and nudge the INR to 2.5.
What is interesting, is that when this sunny spell of weather started on the 31st May, the INR has increased and despite reducing the dose to a sensible minimum of 3 mg., it remains at the high end of the target range.
Obviously, a few days don’t prove it conclusively, but there are other reports on the Internet of the sun affecting the INR. There a thread here.
Note that I now keep the results in a single post here and also with other data like the weather and how I feel in an Excel spreadsheet.
Adverts On The BBC
The only television I watched was BBC World and it was good to see such as Nick Gowing, who I once met on holiday.
However, I was rather fed up with the adverts, for products I weren’t interested in. Although, one was for a mini diabetic meter, much like the device I use to test my INR. Although it was very small. It does show the way these devices are going.
I wonder how long before cruise ships such as the Oriana have a digital television service based on Freesat.
Rat Poison And Sprouts Don’t Mix
This cautionary tale about mixing brussels sprouts with anti-coagulant drugs, like Warfarin, should be noted.
The trouble is that I like my sprouts, so I’ll go easy on them over Christmas.
I think though, I’ll do a before and after INR test.
I feel a bit of scientific research coming on!
Two Parcels From Roche
I thought the Softclix device had failed so Roche sent me a new one. I also needed some lancets, so Roche sent me some of those.
They both arrived the same day as expected, but one was by courier and the other by Royal Mail.
You’d think they’d use one company!
Testing My Own INR
I’ve now been testing my own INR for a couple of weeks now.
Except for my problems with the manual, my biggest problem has been pricking my finger with the Softclix device, to get a drop of blood to put on the machine.
In the end today, I resorted to taking the top off the device and just stabbing the tip of my finger with the lancet. I got a perfect drop of blood, which gave me a good reading with no errors.
I told Roche and they’re sending a new Softclix device.
On the other hand, I’ve had no problems with the Coaguchek device itself.
My First INR Self Test
I’ve just taken my first INR self-test. Or should I say successful one, as I tried yesterday and couldn’t get a proper sample onto the machine.
But today, I thought it through and sat at the table with everything on a clean face flannel. I actually used my gammy left hand to take a sample from the right
I recorded a value of 2.2, which is in my target range of 2.0 to 3.0.
The major problem other than getting the sample quick enough was trying to read the manual whilst I was using both hands to do the test.
The Non-Spiral Bound CoaguChek Manual
My father would be fuming now, as he believed after fifty years in the printing business that all instruction manuals should be spiral bound.
I just proved him absolutely right.
Some people might have worried about making yourself bleed. I didn’t as I spent fifty years badly-biting by nails and fingers. Often until they have bled!
It’s generally all stopped now, although my nails aren’t good, but that’s down to the humidity!
The Anonymous Widower 