INRatio, Protime 3 and Lab INR all different?

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Natanni

Well-known member
Joined
Jun 8, 2005
Messages
580
Location
Northern Minnesota
Jeff mentioned some variablility between the Coagucheck and lab draws...would like to throw out another case :)

Nathan brings his INRatio to the coumadin clinic and tests at the same time; The clinic uses the Protime 3 (I believe it is '3') and there are a few differences that he has noted in obtaining the blood sample; They squeeze the finger many times, form a large drop, wipe it away and obtain a 2nd drop and use this one for the Protimes sample. With Nathan's INRAtio, he was instructed to use the very first sample of blood. If he loses it, needs to start all over with a fresh lancette. The clinic argues that he may get a smidge of alcohol in this first sample, even though he wipes the alcohol off and waits a second or two for drying. When at the clinic, Nathan always uses a fresh lancette for his INRatio sample. Friday's results were the clinics Protime 3 -- 2.8, Nathan's INRatio---2.0, Lab draw (because of nervousness of the coumadin clinic now) --2.4; The clinic decided to bump up his warfarin, as on his INRatio he has been consistantly under 2.5; The coumadin clinic had left his dosage because they had him hovering around 2.8. Sound like the right thing to do to you guys? They were discussing the self testing the INRatio does every time, and that it is different with the Protime 3. We are not familiar with that product, could that account for some of this variability?
 
Sounds right to me. I don't care what you test with, every single one is going to have a different result. If he can test twice with his INRatio and get reasonably close to the same number (.1 to .2), I would consider it a valid reading.

I don't know what Protime uses for a reagent, but I'm told that the INRatio strips reagent is much more sensitive. Whether that is true or not, I cannot say.
 
If you go by the INRatio vs the other tests, the worst that could happen is an INR on the high side of your range. Much better than assuming the INR is too high and lowering the dose.
 

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