I thought I was pretty careful about correctly testing my INR. I've even advised users of the InRatio and CoaguChek S and XS that the manufacturer's instructions say to put the blood on the strip within 15 seconds of incising the finger.
Tonight, I kind of ignored that advice when testing with my InRatio. I incised my finger, but didn't get a very large drop. What I WAS able to get within the first fifteen seconds wasn't enough to be completely drawn in to the strip. I incised another finger, with a LOT of blood flow, and figured that adding to the blood already in the channels shouldn't matter -- the new blood would push the older blood. I was rather surprised when the meter reported an INR of 1.4. The Quality Controls on the strip checked out OK. The blood that was in the strip WAS a 1.4.
Rather than react to that low value, I did a quick repeat of the test with a new strip. (Yeah, the strips aren't cheap, but I wanted to verify the odd result). This time, with an incision in a different finger, I got an INR of 3.2.
Here's what I think happened with the first test -- the blood that was already in the strip had already started coagulating by the time the next drop was added. With the blood already coagulating, the INR determined would have been lower.
My point in even mentioning this is this: if you get a funny result, it is prudent to confirm the value. In my cased, on a Sunday night, after using a questionable procedure to make the first test, it made sense to repeat the test (even if it meant using up another strip).
If an INR is unusually high, it's almost essential to confirm such a reading. (In my case, the blood started coagulating in the strip, resulting in an INR lower than the real INR. I can't think of a case where it's as easy to get an unusually HIGH INR).
Tonight, I kind of ignored that advice when testing with my InRatio. I incised my finger, but didn't get a very large drop. What I WAS able to get within the first fifteen seconds wasn't enough to be completely drawn in to the strip. I incised another finger, with a LOT of blood flow, and figured that adding to the blood already in the channels shouldn't matter -- the new blood would push the older blood. I was rather surprised when the meter reported an INR of 1.4. The Quality Controls on the strip checked out OK. The blood that was in the strip WAS a 1.4.
Rather than react to that low value, I did a quick repeat of the test with a new strip. (Yeah, the strips aren't cheap, but I wanted to verify the odd result). This time, with an incision in a different finger, I got an INR of 3.2.
Here's what I think happened with the first test -- the blood that was already in the strip had already started coagulating by the time the next drop was added. With the blood already coagulating, the INR determined would have been lower.
My point in even mentioning this is this: if you get a funny result, it is prudent to confirm the value. In my cased, on a Sunday night, after using a questionable procedure to make the first test, it made sense to repeat the test (even if it meant using up another strip).
If an INR is unusually high, it's almost essential to confirm such a reading. (In my case, the blood started coagulating in the strip, resulting in an INR lower than the real INR. I can't think of a case where it's as easy to get an unusually HIGH INR).
