temperature and affecting INR

[Sagebrush]

My INR had dropped .3 from last week. I was told it was probably because of the cold weather. She said it makes your blood thicker and your body is producing more red blood cells and then she compared it to flying that is the same thing your body does when you fly in a plane. It makes sense to me but I just had never heard anyone talk about it here. The highs here in Southern Idaho have been 15 to 20 degrees and the lows about zero.....brrrrrrrrrrrrrrrrrrrrrrr.....

[allodwick]

It sounds like this person spent a lot of time thinking about this but started with a wrong basic assumption. WARFARIN DOES NOT THIN THE BLOOD. Never believe anything that people who think warfarin thins the blood say, they have absolutely no knowledge of how warfarin works. It has nothing whatsoever to do with the viscosity of the blood. Warfarin slows down the ability of the blood to form a clot. This is what is measured on the INR test not how thick or thin the blood is. Warfarin is metabolized in the liver. Our bodies are designed to conserve the essential functions - brain, heart, liver and kidneys. Before the body got cold enough to slow the metabolism of warfarin in the liver, your fingers, toes and ears would probably already have dropped off.

A drop of 0.3 is almost insignificant. The test is simply not that accurate. You could put drops of blood from the same puncture on two different testers and get that much variation.

Red blood cells carry oxygen. More are produced in response to the cells in the body not having enough oxygen. There may be some small effect from prolonged exposure to cold but most people have houses heated or cooled to 70 to 80 degrees year round. Just looking out a window at snow or even shoveling a sidewalk will not change your INR.

Red blood cell production takes days. You cannot see any difference in a flight of even a long distance such as to Australia. What might happen on a long flight is that you become dehydrated. This will literally thicken the blood because there is less water not more red cells. Once you get rehydrated they red blood cell count would be back to where it was prior to the flight.

This person would probably make a good science fiction writer.

[Sagebrush]

I was hoping you would reply allodwick !!! THANKS. I know .3 is a minor difference, but I thought her theroy was very interesting. I kind of thought you would say that. I really appreciate your speedy reply.

Faye in Idaho trying to stay warm!!!!

[Ross]

Well Mr. Al why then can I not find any 5W30 Coumadin tablets? :D

[catwoman]

My INR had dropped .3 from last week. I was told it was probably because of the cold weather. She said it makes your blood thicker and your body is producing more red blood cells and then she compared it to flying that is the same thing your body does when you fly in a plane. It makes sense to me but I just had never heard anyone talk about it here. The highs here in Southern Idaho have been 15 to 20 degrees and the lows about zero.....brrrrrrrrrrrrrrrrrrrrrrr.....

Is this the person managing your anti-coagulation therapy?
Hmmmmm.

[Ross]

Hehe, I can get a .3 difference just testing twice!

[allodwick]

We often get a 0.3 difference when we have a person from the lab draw blood in a syringe and put a drop on each CoaguChek-S and take the rest to the lab. This would be 3 or 4 tests and maybe two will be the same. There is no pattern to which tester is high or low.

[Cris N]

I was tested yesterday... 3 times in the span of about 3 minutes. 2.6, 2.1, 2.4. The 2.6 & 2.1 were from the same finger and the same stick hole.

Cris

[allodwick]

Man with one watch always knows what time it is.

Man with 3 watches never knows what time it is.

Man with one test knows his INR.

Man who does 3 INRs in 3 minutes never knows what the INR is.

[Cris N]

Man who does 3 INRs in 3 minutes never knows what the INR is.
Coumadin clinic nurse didn't trust the reading... couldn't believe it was as low as it was... two tests from one box of strips, one test from different batch.

[allodwick]

I can't remember when I rechecked any INR that was below 8.0. It just confuses the issue. I deal with the number that I get. If you just make small changes, there is little danger of causing probalem in the other direction.

Before I went to the meeting last week, my receptionist counted the active charts. We have between 530 and 550 active patients.