Any difference between lab results and home testing results?

[twinmaker]

I have a question. On Thursday, I had my INR done at the lab and the result was a reading of 3.7. Today, I tested on my INRatio machine and the result was 4.6. Is there usually a difference between the lab and the home testing results? This was the first time that I've tested at home and was wanting to try out the machine and this was the reading that I came up with. Did I do something wrong? My instructions said not to press extremely hard on your finger and this may dilute the sample of blood and give inaccurate results. I didn't think that I did this but if I did, would it cause the INR to go that high? Thanks for any help. Linda

 

[karlaosh]

Hi Linda.

I was "given" an INRatio machine at the hospital (actually, I'm part of a study and have to either return the machine next month or get my insurance company to pay for it). I'm supposed to test with it every Monday as well as every time I have a lab test.

I've tested with the INRatio about 10 times now, and each and every time it's read higher than the lab test?as high as one full point above the lab and as little as .2 above the lab. I'd say on average it's about .5 above the lab results.

Several of the Mayo people intimated to me that the INRatio, while easy to use and otherwise a good machine, does tend to read high.

Because it's not been that accurate for me, I think I'm going to return the INRatio machine at the end of the study and, if my insurance will cover it, buy one of the other brands instead.

You might also ask Teddy's mom (skimomck?). I think he left Mayo in May with the INRatio machine as part of the same study.

 

[Ross]

To truly test the accuracy, you'd have to test the same time they draw for the lab. Even then your going to get a different reading. As long as it's with in I believe it's .6 difference, your kosher. I know that seems like a lot, but that's what's in the paperwork.

 

[johnM]

Hi Linda.

I was "given" an INRatio machine at the hospital (actually, I'm part of a study and have to either return the machine next month or get my insurance company to pay for it). I'm supposed to test with it every Monday as well as every time I have a lab test.

I've tested with the INRatio about 10 times now, and each and every time it's read higher than the lab test?as high as one full point above the lab and as little as .2 above the lab. I'd say on average it's about .5 above the lab results.

Several of the Mayo people intimated to me that the INRatio, while easy to use and otherwise a good machine, does tend to read high.

Because it's not been that accurate for me, I think I'm going to return the INRatio machine at the end of the study and, if my insurance will cover it, buy one of the other brands instead.

You might also ask Teddy's mom (skimomck?). I think he left Mayo in May with the INRatio machine as part of the same study.

The Hemosense INratio has good compatibility with for example, the CA 1500 analyser. One can be sure that the Mayo does not use one of these for it anticoag analysis! It would be a good idea to enquire as to the analyser used at the MAYO. It is unfortunate that the values in respect of anticoag are somewhat fluid with the fundimental values available for measuring for example the value of 1 USA gallon et al being in no way similarly available!

 

[geebee]

My INRatio has always read higher than a lab test. I have just made sure I keep my INR on the high end of the range with home testing. The differences have ranged from .4 to .8 higher but I don't care because it's consistent.

Also, who's to say the lab test is correct? Unless the lab uses a similar test, I don't feel an accurate comparision can be made. I am convinced a blood draw test is simply different and both tests are accurate. Do you know how long the sample sits around before it is tested? Maybe venous (sp?) blood tests differently because it is not exposed to air like the capillary blood.

Has anyone here done side by side comparisons with lab draws & other home testers? For example, taken your tester to the lab and used the same blood drawn for the lab test on your home monitor? I think that would be the only way to even get close to an exact comparison.

As with food, drink & meds while on Coumadin, I think the key with testing is consistency. As long as you keep in range, you will be fine.

 

[bvdr]

I have the Pro-time unit and the times I have checked it within the same hour of a blood draw It has been quite close. I've only done this a few times Last year at the VR reunion in Colorado there were three units of different manufactures all set up for us to try. I did all three. The lowest result I had was on the Pro-time unit and that was ( I think) 4.0. I believe the highest was about 4.7 or maybe a little higher. Anyway, it was enough difference to make me wonder......

I remember the comment Rain made the other day about knowing her INR by noticing Petechia and where they are located in helping her judge the validity of her INR. I'm a bit of the same way. If I don't have brusing I will almost certainly find a lower INR when I test. And the same way if I have a lot of brusing I will inevitably test with a high INR. Don't get me wrong though. I dose according to my test results and not my appearance. It just helps me trust the results a little more.

 

[karlaosh]

When I say my INRatio values have consistently been higher than the lab's, I'm talking about labs in three locations: Mayo Clinic, my hometown clinic in Minnesota, and the lab at my cardiologist's office in Colorado.

In other words, I've found the INRatio to be consistently about .5 high when compared to three different labs. (My local cardiologist's lab uses a Coagucheck, by the way.)

 

[Dennis S]

Altitude and measurement differences

Altitude and measurement differences

Does anyone know if the altitude where you live effects the INR? I lived most of my life in Minnesota, most of which is less than 700 feet above sea level. Now I live in New Mexico at 7,200 feet. For insurance reasons, I go back to Minnesota for my physicals. I always have to tell the medical people about the elevation difference or they get excited about my blood work. I don't yet take Coumadin, but wonder if this might have something to do with different test results?

When I say my INRatio values have consistently been higher than the lab's, I'm talking about labs in three locations: Mayo Clinic, my hometown clinic in Minnesota, and the lab at my cardiologist's office in Colorado.

In other words, I've found the INRatio to be consistently about .5 high when compared to three different labs. (My local cardiologist's lab uses a Coagucheck, by the way.)