Monday, 19 October 2015

managing my INR - an example

Well the last few weeks has been a good example of how I manage my INR my self. Obviously the "plain sailing" is easy ...
  1. dish out your pills, 
  2. double check you have the exact correct dose
  3. load them into your daily box
  4. take them

its only when things go 'unaccording to plan' that management of your dose is needed. Such an event came a few weeks ago and now that I'm back on an even level again I thought I'd write this up to assist anyone home managing and self testing to see how I did it (and perhaps include of few of my methods into yours).

This post is an example of the practices I outline in my other blog post about managing INR over here. Central to that is the philosophy of "keep a steady hand on the tiller" : this means don't be micro managing adjusting (tinkering all the time) and don't be adjusting too much (meaning the dose size change). To quote from there some relevant points:
  • keep your doses steady, by this I mean take the same number mg per day. I feel there is evidence to support that alternating high / low doses lead to increasing instability
  • there is a natural swing in range of INR which will occur even with the same dose. Accept this and don't try to micro-manage it
  • measure frequently (like weekly or fortnightly not monthly or bi-monthly)
  • if there is a trend which worries you, measure more often (such as again in 3 days) to see if the trend is continuing or returning of its own accord (it may well just do that)
  • adjust doses in small amounts, such as 0.5mg per day.

So this is an example of what happens when I do a mid week measurement based on an INR which I feel warrants it.

I do my testing every Saturday morning, and write this into a spreadsheet, write in my intended dose for the week and move on.

So I found the other Saturday (12 Sept 2015) that my INR had risen from 2.8 to 3.8 since the last check. My preferred range is between 2 and 3 (although in practice I don't really care if it dips a little either side of this.

The Y axis scale of my graph is omitted to keep the image compact, but the X axis represents week number starting on the first Sat of Jan.

So the red arrow points to the 3.8 reading, the dose line (red dotted line) has been consistent at 7.25mg for weeks. The lows in that graph are around 2.1 and the highs are about 3, so you can see that its "normal" for me to bounce around within my range.

You can see a few more readings following, which break out of that "stasis" that I'll go into now. The reading of 3.8 on the 12th was a signal to begin what I call an Adhoc monitor, where I increase the INR tests from weekly to twice a week. When I see something high like this, I like to follow it and see within a few days (like 3 or 4) if its going to return lower on its own ... most often this is exactly what happens.

Mostly no change is needed and it corrects itself. This is the best option ... leave it alone if you don't need to change it.

However since this occasion was nearly 4 I thought I'd also drop only my next day dose to 6 from 7.25 and check again on Tuesday. The logic of a single dose reduction is that it will have a quick effect on reducing your INR, it will then resume back to where it was going to "level out to".

Of course this is where you ignore the conventional "knowledge" that INR does not respond fast, as that is wrong.

This graph below shows the progression from the 5th of September (INR = 2.8) through my AdHoc monitor. It shows the dose in mg on the right hand Y axis (as a red dotted line) and the INR on the left hand X axis (as columns).

After my dose reduction my INR moved back to 3.2 (still higher than I wish). Note that I did not alter anything again yet. Butand by the next Saturday had gone back up to 3.7 again. Clearly this wasn't going to be returning any time soon, so it time to take a little bit of action


From this I decided that something more consistent had changed with my metabolism so I thought I'd drop my dose on that Saturday to 4.5mg and continue at 6mg for the time being and continue my adhoc frequent measurements. Of course I also wrote the Saturdays into my normal sheet (and you can see that in the first figure above where there are 2 high readings).

The following measurements were trending in the right direction (under 3) which you can see above in the graph (if you weren't taught graphs at school I encourage you strongly to learn to read them, its not hard children do it). However the trend down started to head too low and so when on the 3rd of October I got a 1.9 I decided that I'd revise my daily dose up a smidge to 7 daily and see if that found a better balance. You can see that it did.


So you can see  that I've now changed my dose from 7.25mg (administered as 7.0 alternating with 7.5) to 7.0 daily and my INR is now meandering around the 2.4 area, which is (to quote Goldilocks) just right.

So looking at the second chart again:

we can see (starting at the left) that my INR bounds were creeping up to be between 2.8 and 3.8 ... my adjustment down corrected that, but to my mind it was still sloping down (the green line) and so I stepped my dose up a bit. I moved it to less than it was before, but still up by a little more than 10%. That's not a rule, its just a guide.

To my mind something seemed to happen to my body during this period and without action my INR may have been between 4 and 5 which is higher than I would be comfortable with. If one was measuring once per month it is easy to see that you could have measured 2.8 and then been over 4 for weeks without knowing it.

This is exactly why I advocate for weekly measurements, and if you are self managing then increasing your measurements in the face of events so that you can learn - but you must be structured and documented or you're just wasting money on strips.

Its also worth mentioning that this is exactly what INR clinics do. They

  1. look at the measurements
  2. Determine a trend
  3. Adjust dose as required
They do not have any more magic than that. But unlike you they don't really get to know you. Which is why they may make more changes than you would. Wouldn't you be happier with an extra finger prick than an extra vein draw to get this data? I know I am.

This is also a good example of why you don't use massive variations in dose, such as  5mg one day, and 10mg on another day. There is just no way you can expect to ever be stable or reliable with such input variations.

So now
  • my INR is now exactly where I want it to be
  • my INR did not stay too high or too low during the adjustment period
  • I have found and established a new stable dose
No problems, no "bleed events", no bruises (even though I was working on my motor bike engine and bashed myself many times) ... all because I was monitoring and adjusting with care , caution and diligence.

I hope this helps you to do the same



It is now Saturday the 24th of October and my INR reading this morning was 2.2 with a weekly dose of now 7mg shown above. I seem to have gone back to my normal metabolism again, so I'll resume my 7.25mg per day dose that I was previously on.

This of course begs the question of "should I have done nothing" and "was there any point in knowing".

My answer is this: If I had done nothing my INR could have remained above 4 for a few weeks. This is not in itself a significant problem. But if I'd had an accident (say a motorcycle or car crash) it could have exacerbated any inter-cranial bleeding and thus brain damage.

Its true that mostly we don't have accidents, but do you wear your seatbelt most of the time? If you do then you'll know that wearing it only matters if you have an accident.

Thus I like to keep my INR below 3 most of the time.

Just be sure that you don't over manage it, look for trends and adjust in small increments.

In hindsight I think that dropping my dose to 6mg daily after I took action on the 19th was perhaps lower than I should have done for the smoothest possible outcomes. Next time I'll drop it to 6.5mg instead. Of course there was nothing "wrong" with being between 1.9 (the lowest recording) and 2.3 ... its a good result too.

Best Wishes

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