INR all over the place

[Bluespit]

My daughter 22 years has a mechanical mitral valve since 2013 and for the first 10 months her inr was fairly good, her range being 3-3.5 All this was in Spain where the surgery was done. Now that she has relocated to London for studying since 2014 the frst few months everything was fine.She takes sintron and in the UK they kept her on it is tea do changing to warfarin. Now over the last 10 months or so the reading has gone as high as 7.9 and as low as 1.5 this week. All they seem to do at the clinic is adjust her dose. We can't understand why as she hardly drinks at the most a beer and that is on very rare ocasión, eats healthy very little meat, eat vegetables and no dairy products. As I live in Spain her last call after the test upset me deeply.She said mom how do I know some thing is wrong when the are no symptoms that my blood is at 1.5. Am a very distraught mother

 

[pellicle]

Hi

I'm sorry to read of your woes with INR. I have a blog which has a lot of useful points about managing INR

http://cjeastwd.blogspot.com/search/label/INR

Start there and see that through with a careful eye.

The simple strategy is to keep dose regular and adjust only as needed.

Watch out for grapefruit juices and some specific mandarins. They can send your INR high.

I knowthere are many myths with respect to what influences INR, my blog posts discuss that a little. The key to understanding is only two things influence this: vitamin K and the Hepatic enzyme pathway called P450.

Generally diet has little to do with it. Meat has zero to do with it, eat more to get iron. vegetarians can suffer from deficiencies of vitamins. Is she eating huge amounts of Spinach?

Contact me if you have any questions or want to chat.

 

[pellicle]

Just a quick follow up for the interested reader.

The lass in question is not on warfarin, she is on an anticoagulant called Acenocoumarol marketed under the name "Sinthrome" (much like warfarin is marketed under "coumadin")

I'd not heard of this one before, so I looked it up. Unlike Warfarin, Sinthrome has a very short half life in the body, about 11 hours (vs warfarins 40 hours).

So, this means that if you miss a dose on Sinthrome your INR will drop like a stone.

I knew that Phenprocoumon was more common in Holland and Germany, but I'd ignored Sinthrome in my readings.

For the interested the half life of each of these is:

Anticoagulant used	Biological Half life (median)
Acenocoumarol	10 hours
Warfarin	40 hours
Phenprocoumon	132 hours

Personally I can see why warfarin is the most popular on the planet. A reasonable half life (making reversal management easier) but balanced against "whoopsies" which makes Phenprocoumon one of the easier to deal with ... missing a dose would have almost no effect. Acenocoumarol on the other hand seems like a roller coaster to me... A missed dose and you drop INR like a stone.

Also the dose on Acenocoumarol is very low on average (something like) 40% lower than that used on warfarin to get the same INR. So that means tuning your dose is even harder than it is with warfarin; for an example making a 10% change in a 2.5mg dose means dropping to 2.25mg . Considering tablets seem to be 4mg, its Mission Impossible if you ask me. (Like we said at the theme park I worked at during my University days: keep your hands inside the ride at all times)

I can't see a reason for Acenucoumarol which perhaps explains why its only used (that I know of) in a few places...

Interesting