The INR can drop sharply and I have a concern.
Example I do a test on Friday and I find INR 2.4 the next Friday it is 1.7
Firstly, I want to be sure you're on warfarin and not Acenocoumarol, but yes, things like that can exactly happen, its uncommon and not universal, and so exactly because it is unpredictable we have to do things
like gather statistics. This is also exactly why I strongly advocate for weekly testing. I also strongly advocate for keeping it all in a spread sheet and looking at the data (not with dull dead blind eyes but with the eyes of interest). I go a lot further and involve a simple data model.
There are many factors possible so I can't hypothesise every possible scenario around your example, but suffice to say that its
very unlikely that on Saturday it fell to 1.0 and stayed there and then suddenly on Thursday spiked back up like a rocket launch to 1.7 from 1.
Systems just don't work like this, not without some sort of provocation be that diet, drugs, illness, alcohol ... and you should be aware of what foods or "out of the ordinary" things that occurred around it.
IF you utterly can not come up with anything, what stops you from measuring mid week? Totally doable if you ask me and you'll notice when I presented my "Adhoc samples" I measured more frequently
exactly for those reasons.
No one knows how much it could have been in the previous days, it could have been 1.5 on the previous Tuesday, etc.
So taking a dose of heparin protects me because I might be >2 on Sunday so I might already be over a week <2
I would like your opinion,
well heck, if we just look at numbers it could have spiked up to uncoagulatable (IE >10) and then dropped back ... we just don't know.
Which is why if you suspect something is happening I say again "test more often".
For me personally I have never seen more than 0.7 INR units per day and certainly not without something like a missed or a double dose or drinking a gallon of grapefruit juice, eating a bunch of Vitamin K supplements ....
If the person does not have a triple redundant system then you simply can't rule out "forgot" or "forgot I took" or even "took wrong dose". Again, this is why I advocate for:
- determine dose for the week ahead (based on an INR measurement and an evaluation of your history)
- distribute that dose into your pill box (double check it) which is clearly labelled for the day of the week.
- daily, take your dose, check the day, again check the dose and leave the lid up after taking
This has the following redundancy checks
- visual confirmation of taking and day of taking
- visual confirmation of wrong day taking
- confirming that you only take exactly one administration (not two or less)
- confirmation at least twice of exactly taking the correct dose (mistakes happen, despite colour coding of pills)
its a simple and proven system
Surely someone increases the dose of warfarin and does a test to see how much the INR is, there is concern that the INR may have been <2 for maybe 7 days?
I'm having to make a guess at the exact meaning of the sentence above, but in my view before changing a dose you need to have more evidence and first step is to assume its not a trend but a single event (high or low). I make an adjustment for 1 or 2 days, then resume that week on prior. IF and only IF (IFF) the INR is
back where it was , then we can be more confident that its a change in need and make the adjustment again at next administration is more data driven but yes, and with a dose change you should be careful. I have a good idea that most people only make adjustments based on what amounts to nothing more than gut feel and certainly nothing data driven. In the main that may be sufficient but I don't feel confident. I don't feel confident because many people are bad with gut feeling driven cooking adjustments (add a little more of this, oh that's ruined it).
One needs to be experienced
and have a good memory.
Alternatively I train people with a data driven approach. Reach out if you want to work with it.
For the reason, because I don't know when I will be >2, a low dose of heparin will help me psychologically as I am protected until the INR increases and INR >2
each to their own, but I've already covered why I don't think that is needed.
https://pubmed.ncbi.nlm.nih.gov/20598989/
Results: We analyzed 396 patients (197 in the LOW-INR group and 199 in the CONVENTIONAL-INR group). The mean of INR was 1.94 +/- 0.21 {note: this implies 1.72 was seen} and 2.61 +/- 0.25 in the LOW-INR and CONVENTIONAL-INR groups, respectively (P < .001). One versus three thromboembolic events occurred in the LOW-INR and CONVENTIONAL-INR, respectively, meeting the noninferiority criterion (P = .62). Total hemorrhagic events occurred in 6 patients in the LOW-INR group and in 16 patients in the CONVENTIONAL-INR group (P = .04).
In my view a person does not get a stroke from being INR ~ 1.7 for a day, you get something like that for being like that for weeks.
You may be familiar with another risk assessment methodology is a Sievert; this is defined as intended to represent the
stochastic health risk of
ionizing radiation, which is defined as
the probability of causing radiation-induced cancer and genetic damage.
Its important to understand that its probabilistic. Its non trivial, but you can read about it
here. Importantly its not just about the amount of radiation, its about the duration of that (and other things).
Again I am not telling anyone what they should or shouldn't do except to say: if in doubt test and see.
Reach out if you want to have a go at what I do.
