You can't always trust the labs

[Protimenow]

My latest update to this already old thread:

I had a blood draw last Friday (July 19). A few hours later, I tested my blood with my Coag-Sense PT2.

Today, I learned that the lab said my INR was 3.88 with a PT of 40 seconds. This is the same lab that returned a 3.5 when my meters showed 2.8 and 3.0.
Last Friday, my Coag-Sense meter showed an INR of 2.8 -- a full point below the lab.

I tested again today using my PT2 and original Coag-Sense meter -- I got 2.7 and 3.0. Although the two Coag-Sense meters are about 10% different, this isn't troubling.

My regular testing with the PT2 consistently puts my INR between 2.7 and 3.0.

I told my doctor that the next time I get a blood draw, I'd be interested in the values that he gets if he sends the blood to two different labs.

I'm more comfortable with my meters than I am, now, with the labs.

 

[carolinemc]

So, by your reasoning, if you increase the amount of exercise, your INR will go up. Conversely, if you decrease the amount of exercise, your INR will go back down?

Me doctor ('ask you doctor') wouldn't have a clue. I can only learn that he knows little about INR. And, as far as I'm concerned - consistency IS important. (I'm assuming that you left out the word 'learn' when you said 'ask you doctor and you will something new' - Right?)

Increased activity, which will necessarily cause you to eat and drink more (and different?) foods, may have an effect on INR. Similarly, if your exercise suppresses the work of the digestive system in metabolizing warfarin (just as antibiotics kill gut bacteria that also have an impact on how warfarin is broken down in the body) may have some effect. I personally haven't noticed any difference in my INR regardless of amount of exercise.

Has anyone else reading this thread had experience with INR increases as a result of increased activity or INR decreases when activity is reduced?

I don't have time right now to explore whether there's a linear relationship between increasing activity and increasing INR.

I just noticed your comment, been off the board for a week or so. You said some true facts. I get higher readings when I start getting active. I had to tell the lab people to explain that I was not on antibiotics so they would not yell at me. And recently, I was on antibotics and had a reading of 1.8. Then we rechecked two weeks later and had the same reading. We changed dosage and I recheck on Monday. Hopefully, I will get a more normal reading. I have tried to get out more, but not everyday. Walking is the main exercise. I will be doing more soon. Thanks for sharing the facts. I had to learn things the hard way. Hugs for today.

 

[carolinemc]

Nope. No effect. When I get my fat arse into gear, I see no change in INR.

Depending on the activity and how often you do it. Walking everyday will have a little effect on the INR. Ask your lab person or doctor. Education is the key. I used to walk everyday and in had an effect of increase on my INR.

 

[Protimenow]

I doubt that a lab person would have a clue, and have serious doubts if doctors do, either.

 

[carolinemc]

Went to lab today, they use the meter and this time instead of a 1.8, it read 3.0. But do not have to retest for three weeks. I trust them since I can get the reading then, instead of a lab who takes forever to get the reading. And they dose me on the spot. I will keep you all posted on my INR. Have not had these readings for some time. But I trust the lab people, more than the doctors.

 

[Protimenow]

Caroline - when I went to an anticoagulation clinic, they used a meter that was designed for hospitals. It was the kind used in operating rooms, and frequently calibrated.
What did your clinic use? I would be somewhat surprised if it wasn't a CoaguChek XS.

Your result put you at the high end of your range - I hope they didn't reduce your dosage by very much. (If they reduced your dosage, and don't retest for three weeks, how are they going to know how low it'll drop? What they changed is probably OK, but if it was me, I'd be more comfortable doing self-testing just to make sure their dosing changes weren't too much).

 

[carolinemc]

Caroline - when I went to an anticoagulation clinic, they used a meter that was designed for hospitals. It was the kind used in operating rooms, and frequently calibrated.
What did your clinic use? I would be somewhat surprised if it wasn't a CoaguChek XS.

Your result put you at the high end of your range - I hope they didn't reduce your dosage by very much. (If they reduced your dosage, and don't retest for three weeks, how are they going to know how low it'll drop? What they changed is probably OK, but if it was me, I'd be more comfortable doing self-testing just to make sure their dosing changes weren't too much).

they use CoaguCheckXS. Not a high end. They did not reduce the dosage, it was upped as a matter of fact. I trust them completely on this. They know what they are doing, better than Lab One, who always took through the arm and I would wait forever and a day for the results to be sent to the Cardio office and then the nurse, who did not know anything, would dose me over the phone. I quit that and went to the hospital at KU Med in KCKS. They used the meter. I know go to a teaching school, Truman Medical on Hospital Hill in KCMO. They also use the meter, but they dose me right no the spot. If I have any problems, there is the emergency room close to me at North Kansas City Hospital. So all bases are covered, friend.

 

[Protimenow]

I've gotten to the point where I'll trust the meter before trusting the labs. That said, though, it's still an issue where the XS usually reports higher than the labs. But, OTOH, both are usually within an acceptable margin of error between each other.

My old anticoagulation clinic, associated with UCLA hospital, also prescribed any dosage changes on the spot.

I'm still not comfortable with retesting every three weeks (although I've sometimes done it, with no negative consequences). I still feel safest with weekly self-testing.

I'm glad to read that you've covered your bases.