Unexpected and Question

[Gnusgal]

Okay, I know I should have expected it, but I didn't. I have now stuck myself for my ProTime three times. The first being me just trying it out, the second on the phone with the QAS nurse, and the third right after because I got an error. I now have little circle bruises on the tips of my fingers. I expected them to be sore, but I've never gotten visible bruises from finger sticks before. Guess it just goes with my other bruises (though none can compare to the DARK purple one on my upper arm).

Anyway, my INR earlier this week when I checked it (Monday, I think) was 2.4, yesterday it was 2.5. So I'm consistant, but the question is, how close is it to the lab??? I'm thinking my INR at the lab will be a bit higher, but I'm not sure how much. So here's a question, once you find out how the ProTime compares to the lab, do you adjust in your head what your "actual" INR is, or do you just go by what the ProTime says??? I suppose I'll talk to my card about it tonight when she calls to tell me my lab results. I plan to take my machine with me today and do a comparison.

I had also planned on going to talk to the rehab people about starting a program (I have a prescription from my card now), but I'm not sure I'll have time, since I told the QAS nurse to call me tonight at 6:30. I had her call early so I could go out tonight, but that may be too soon to be back from the rehab place... I'll let you know what I do.

Thanks for everything,

[Gnusgal]

Okay, I just got to work, and now my nose is bleeding! I never get nose bleeds. If my INR was 2.5 last night (which is my bottom limit) then why would my nose bleed??? I'll be calling my card later today, but I needed to "yikes" a bit.

Thanks,

[Creed3]

Niki!
I can't really answer your question about the ProTime machine. I am just now starting to look into getting one, so I have alot of questions too.
I too have just recently started to get nose bleeds. Pardon me for asking, but is it just when you blow or wipe your nose or was it running out of your nose? My nose bleeds were just when I wipe or blow my nose. I never used to get nose bleeds. I had my INR checked and I too was at 2.6 and 2.3, right where I should be. Confusing isn't it. Why the bleeds then? Well, I would definately check with your doc. Let us know how things go.

Take Care!
Creed/Gail

[Christina]

Nikki,

Who cares how close it is to the lab!You have so many variances there. Just trust YOUR machine otherwise it'll drive you crazy and your doctor will give you a hard time as well. I want to remind you that most doctors don't like hometesting because that is taking money out of their pocket.
I have been home testing since Janaury 2001 and have seen the inside of a lab in 15 months. I hope I can keep it this way. My doctor doesn't mind either, and I don't ask too many questions becasuse he might change his mind. What you have to go by is HOW you are doing. Are you eating about the same amount of vitamin K per day?
Little nose bleeds happen and often is because of dryness and not because of INR. With an INR of 2.3 -2.4 it is highly unlikely that the nosebleed is as a result of your high INR.
Again, TRUST YOUR MACHINE.

Christina
AVR's 8/7/00 & 8/18/00
Tucson, AZ

[Blanche]

Nikki:
I agree with Christina. You must trust the method that you choose. There is no way to "adjust" INR results from the lab and from your machine. We spent 6 months comparing lab results and Protime monitor results and there is no way to compare them. I believe the monitor is more accurate because there are so many variables to be accounted for in lab tests. We once sent samples to two labs from the same draw and got different INR values. Another time the lab reported 8.2. A second lab result done STAT one day later resulted in an INR of 3.8.

Christina is also right about freaking out the doctor. We have a doctor who is so agreeable, accessible, and caring that I love him more than the piggie loves the mud. Yet, he is still concerned about home testing. After l9 months, he still gets a bee in his bonnet from time to time. Home testing has been done in other countries for years. Currently there is a study being done in Germany with 70,000 people. In the US home testing does not have a long track record and most doctors do not have the experience base to be confident....and many are just not adequately informed. The most important issue is for you to be comfortable with the method you choose.

As for nose bleeds, at this time of the year I get them frequently. I convinced that mine come from allergy medications that dry me out too much. Happens alot in spring and fall for me and I don't take blood thinners. Good luch and best wishes.
Blanche

[LUVMyBirman]

Christina has some very sound advice. Take it! You should have a lab draw every six months to make sure things are in check. There will be a variance. You could visit three different labs in a day and obtain varying results. It's not down to an science..... so I have finally come to the conclusion NOT to expect perfection.

In reference to your question about the nose bleeds. I have been getting a little when blowing my nose first thing in the AM. Normal INR. You have to remember, most of us have just turned the heat on for the winter. That's when it started for me. We do have humidifiers on our furnace.....need to check to be certain they are working. I did not have this problem living in Tennessee. Drier climate up north.

[Michele]

Dear Gnusgal,
Please call us at 1-800-298-4515 we would be more than happy to send you samples of Tenderlett Juniors to see if they work better for you than the Tenderletts. You do the finger stick with the juniors and still use the collection cup on the Tenderletts to collect your blood and snap into your machine. We also would be happy to discuss variances with you from the lab. You might get two different readings even from the two top labs in the country just by different ISI, time of day, things you ate - you just need to trust one method.

[EVELYN]

Hi Niki

We have been exactly where you are now as far as the differences between Protime and lab/coagucheck. After many calls to Protime, we finally got some answers from a wonderfully nice gal who told us that the difference between the Protime and Coaguchek was about .6666. There is also a plug that your cardio can request to change the Protime's ISI of 1 and the Coagucheck's ISI of 3 to put them in line. We had planned to do that, but now we just add .6 on and go from there. I think Christina's words of advice were the best, JUST TRUST YOUR MACHINE. I do make a habit of faxing in Tyce's results to the cardio every few weeks or whenever he is not within 2.5 to 3.5. They return my call and we adjust meds or eat salads or have an extra glass of wine---whatever works. We love our machine. Just got back from Virginia, had it with us, checked the INR and just continued on. The peace of mind is absolutely worth it. Good luck with it. As far as the nosebleeds go, check with your cardio. Evelyn

[Ross]

Okay, I just got to work, and now my nose is bleeding! I never get nose bleeds.
1. Stop picking your nose. :D
2. You just got to work and your anxious. Your blood pressure just shot up and the inside of your nasal passages are dried out.
Guess what-Perfect scenario for a nose bleed! :)

The question is, did it stop in a relatively short amount of time or was it one of those bleeds that make you wonder if you shouldn't head for the hospital?

I know I had one not long ago that didn't want to stop (INR was 4.4 at the time). I packed my head full of gauze and Kleenex and it stopped about 2 hours later. My problem is this oxygen drying my sinuses out. I have a water bottle added to the system, but I don't think it does much of anything to relieve the dryness. :o

[Granbonny]

Are you using the same finger..switch off..bruise will be gone in a day...Nose bleed has nothing to do with INR..It would be on HIGH side. You bleed when your blood gets thin..HIGH INR ( I think:confused: HELP Al..:D I asked you before..but don't you have a gym at your school..walk after school is out..ect..Why go home, back out to Rehab, home again..I never went to Rehab..Just Walk...We have several cute water fountains around inside our house. Keeps moisture inside...Plus drowns out my clicking:D Bonnie

[Johnny Stephens]

I haven't had a nosebleed for several hours now. Seriously, my numbers are in the 3.5 -4 range, I get the pink hanky all the time. Only a couple of out and out nosebleeds in six months, but then, it's nice and moist up here in Seattle :cool:

[Nancy]

Here's some info. that saved Joe from having to go to the ER when he had a mammoth nosebleed. He's got a "bleeder" in his nose that opens up on occasion. Of course, if it doesn't stop and you are losing a lot of blood, you must go and get it taken care of.

http://www.doctorhoffman.com/epistaxis.htm

[Blanche]

Evelyn:

There is nothing that one should do to an INR. There are no conversions and there are no formulaes. You are, once again, giving dangerous advice to people here. I think you misunderstood. What do you do with the .6? That is 60%. So, if an INR is 2.5 on Protime, you adjust by 60% or 6666%? The plug you talk about is for professionals, meaning trained, professional medical personal including doctors. My husband's INR is currently 4.1 on the protime. Should I multiply it by .6666? That would mean that he is at 2.7.One is in range and the other is not. If we followed your advice, and it is misguided, we would find ourselves in the same position that the people were in pennsylvania when lab results had errors and people died.

Stick to what you know. As I wrote in the past, there is nothing, nothing, nothing that one does to an INR.l There are no accepted conversions, there is nothing to do but read the results on the monitor. To advocate anything else is misguided and dangerous.

Evelyn, You are one of my favorite people here and I so enjoy youand your posts...and I remember the first one. Stick to what you know.

[Gnusgal]

Alright, I'm home from work (finally!) and can finally sit down to the computer. My nose bleed just freaked me out a bit, because it was different from the "dry weather" nose bleeds of my past. But it stopped after a little while. Wasn't flowing or anything, just discovered it when I sneezed. I'm not too worried, and did not get a chance to talk to my card today (though she should be calling some time this weekend to give me my INR results from the lab, and I'll talk to her then).

As for the ProTime, I did three tests today. One right after my blood draw that read 2.0, which seemed way off to me, so I decided to do it again right then (I brought two of everything just in case something went wrong) and got an air bubble. So I had to wait until I got home (about an hour later) and do one once the cuvette was out of the fridge long enough. That one (with the QAS nurse on the phone with me) went fine and read 2.6. I'm much more tempted to believe this one, since it is close to the number I got last night (2.5). I don't understand why it would read 2.0??? Did I do something wrong? Anyway, I'm still working on figuring this thing out.

As for my finger bruises, yes I'm changing fingers. but after doing six sticks in one week (because of training and errors) I'm running out of places to go. ;)

-----------------

My card just called with my INR results! I had a 2.9 from the blood draw. So we are going to compare the lab and ProTime again next Friday, but she doesn't have a problem with the difference, since they are both within range. I know you guys are always talking about your docs who don't like home testing, but my card was actually the first to suggest it to me when I got started on coumadin. She's great. I don't think I'll ever be able to move out of this city, because I don't want to have to find another card. She's the best!

Anyway, thanks for all your responses. You really are a great bunch of people!

[Gnusgal]

I didn't mean to not answer your question, but got distracted when my card called. The school I teach at probably has some equipment, but I have never used any of it myself (I've never been able to exercise much- never even took a PE course) and I would feel uncomfortable going in and using it while my students were around (and the 7th grade athletics is in the morning, 8th in the afternoon). My card decided rehab would be a good idea because of the problem I may be having with my paracardium. And I think it would be good if I can find out what is going on that is making me so short of breath. I know that just going out and DOING something would be helpful, but I have to be honest and say that once I'm home there is little hope of getting me active, because I'm SO tired by the end of the day, and there are no street lights where I live. I think rehab would be a motivator and help me to actually see results. I've had other OH surgeries, and managed to do fine without rehab, because I started doing more on my own. But that was back in college when I actually had time to take naps durring the day, and then go to a pool to swim. I'm hoping to not be in rehab all that long, just until I can feel comfortable with what I should be doing and then I will probably look into going to the gym at the local college (where my husband attends). But first I want to feel comfortable with what I'm doing and not put myself at risk. Besides, the rehab place is MUCH closer to home than the college, or my school.

Oh, and I don't intend to go home, then to rehab, then back. I probably wouldn't go if I did. I intend to go straight to rehab from work. You're right on that one.

Thanks for the suggestions!

[EVELYN]

Hello Blanche

The last time people on this list questioned the INR and comparisons with Coagucheck and Protime, I contacted Protime and spoke with a lovely gal named Lakeesha at extension 274---actually both my husband and I spoke with her. We queried her about the difference between the two machines and her answer to both of us (after much debate within the office) was to ADD .666 to the protime INR and it should equal the difference between that and the Coagucheck machine; meaning if the Protime tests 2.0, the Coagucheck will test 2.6. We also did a check of the two machines at our cardio's office from the same blood draw and the difference between the 2 machines was exactly .6---Protime being lower than the Coagucheck.

She also told us about the plug that our cardio could request to bring our Protime and the Coagucheck machine that our cardio uses in line with each other. All your cardio has to do is write a letter to Protime and they will send the plug---you then bring your machine to the office and they will adjust same--no additional fees involved. We were both very satisfied with her answers and decided NOT to have our cardio request the plug because we knew, based on Protime's advice, not my conversions, that the difference was very easy to figure out.

I do not feel I am giving erroneous information, Blanche. The reason we contacted Protime for a second time was specifically to question the differences between the two machines. What I have stated above is EXACTLY what they told us, almost verbatim, as I wrote it down in shorthand on the file folder we keep all the Protime information in.

Evelyn

[Christine]

hi niki,

i just tested at home on both the 3 and 5 channel couvetts.. my numbers from the lab vrs the 3 channel were not even consistantly off, so QAS sent me some 5's yesterday.. today i did them back to back and got the same results.. even though my doc goes by the lab results..he knows i have this machine and was just waiting until it's more in line.. but i'm beginning to believe what the others say.. i'm not going to get a consistant reading between the lab and at home.. seeing the same result on both channels kinda reinforced my confindence with the machine.. but i go back to labcorp in plano this week and i'll test both couvetts again then.. i might go across the street to hospital area and get it drawn by another lab (one my GP not Card uses) at some point in time to compare.. but since my draw is not stat, and with labcorp i believe the all the tests are performed at medical city (their main office) the time lasp might be the culprit also.. (i'm going to call them to confirm their testing facility)

sorry, but i forgot.. do you go to a coumadin clinic or lab... also, you mentioned your husband goes to college... just out of couriousity (sp? - mind freeze there) which college does he go to.. my boyfriend works at UTD (central energy plant) and i've been thinking about going to back to school to get my second degree in either radiology or sonagraphy/echocardiography at the dallas community colleges - we're also looking at moving into the collin county area (townhome/house to rent) in the spring, so i'm debating that issue as well.. dallas vrs collin county rates for community colleges..

anyway, hang in there.. i promise you the brusing will and does go away.. but they are correct when everyone says to stick yourself in the upper middle area of the tip of your finger.. more fleshy, easier to get blood and it doesn't hurt as much..

chris

[Ross]

they are correct when everyone says to stick yourself in the upper middle area of the tip of your finger.. more fleshy, easier to get blood and it doesn't hurt as much..
Yeah, what she said. Stick it, poke it, jab it, have fun with it. :D

I'm just jealous that I'm still getting 24 gauge (23 1/2 ?) needles poked in my arms and I hate it! :mad:

[Gnusgal]

Chris--
I go to a lab (Lab Corp IN the Plano Hospital) and get arm sticks. My card wants me to go to the lab at least one more time, to check the difference between the lab and ProTime, but she's confident that I won't have to go very often after that. Yeah! You're right about Lab Corp, they do send the blood to the main hospital to get the results. I have all kinds of problems with them. I have standing orders for them to be stat, but on more than one occasion it has not been done right away.

As for my husband, he goes to CCCC (Collin County Community College), and is currently on a track to go into nursing, but will most likely change to radiology or sonography (isn't that a coincidence?). We live in a duplex very near the hospital (about 5 minutes away). We could be neighbors! ;) The street we live on is all duplexes and there is always at least one with a For Lease sign outside. It's a nice area. My husband attends classes at the Frisco campus, which is only 15 or so minutes from here, but I know the nursing classes are at the McKinney campus, which would be just a bit further. Don't know where the sonogorphy and radiology courses are held. But all of the campuses are not too terribly far from us.

Everyone--
Anyway, thanks for the words of wisdom everyone. When I think about it, the difference between the ProTime and lab draw was very small (only .3 off) and I think I'll be comfortable with that. And I figure, once I'm only sticking myself once a week, instead of six, my fingers will forgive me. :)

[KIRSONRON]

I'd like to reinforce what Blanche said - INR is a normalized ratio that once calculated, allows a direct comparison between readings, regardless of the variation between the ISI of the reagents used for the testing. I believe that any difference between ISI reagents shows up as a change in clotting time. By knowing the clotting time and the ISI of the reagents, the INR can be calculated. Therefore, INR is INR - regardless of any difference in methods or reagents used for the test. The INR was developed to allow a direct comparison of readings regardless of which lab did the testing or any differences in their reagents. If you are given an INR reading, it has been corrected already for any differences in methodology. Don't mathmatically correct this number or you will get yourself in real trouble.

[Granbonny]

Stick it..Poke it..Jab it..Have fun with it..What are you talking about???:D :D I thought I had you improving ..Careful I may have you in lock up again:D :D Bonnie (Resident's Nut's Therapist)

[EVELYN]

I just got off the phone with Lakeesha from tech support from International Technidyne Corporation in New Jersey, makers of the Protime machine;(732 548 5700 x 274) basically because I was pretty sure of what she told me the last time I spoke with her, but wanted to verify the information I was told a few months ago. It absolutely is NOT my intention to give misleading information to anyone on this list.

Here is what she told me: The Protime machine has an ISI of 1.0....the Coagucheck has an ISI of "around 2." If you test on both a Protime and a Coagucheck with the same blood draw, the difference can be UP TO A .6666 RANGE between the two machines, Protime being lower.....ie. if Protime gives an inr of 2, Coagucheck will usually give an inr of up to 2.7.

She also said that within Protime, the cuvettes also can make a difference. The 5-channel cuvettes can test lower than the 3 channel cuvettes.

I do not think I heard it wrong a second time.

Evelyn

[KIRSONRON]

Again I think you are being given incorrect information. I have the ProTime Operator's Manual in front of me now. This booklet is written by ITC and was published in July 2001. It should have come with your unit - it not, you can obtain an Adobe formatted version from ITC's website. On page 35 in the "For Professional" section, the relationship between INR, ISI and Prothombin time are clearly defined. Let me quote you some of their writings "The INR system was introduced by The World Health Oraganization to standardize PT (prothombin time) reporting such that patients could be unifrom accross different laboratories". In the past, PT was used to report clotting, a time value that varied with the ISI that the laboratory used. This was very confusing to doctors since each lab used a different strenght reagent - (different ISI). The INR eliminated this variation by converting all prothombin times to an International Normalized Ratio (INR) based upon a calculation that took into account the ISI of the labs reagents. This formula is also shown on page 35 What I think ITC was trying to say is that if you look on page 36, you will see a table showingthe relationship between PT seconds vs. ISI - for various INRs. Choose any INR in the right hand column - for example 2.5. The PT for an ISI of 1.0 is 32.6 seconds while the PT for that same INR using an ISI of 2.0 is 19.5 seconds or approximately .666. Using the programming plug to change the ISI of the ProTime forces the machine to report an adjusted prothombin time - again on page 35 this is quoted ..."Since results reported i PT seconds depend on the sensitivity (ISI) of the reagent employed, the physician has the option of changing the ISI value in ProTime so that the ProTime results reported in PT seconds closely match the results reported by the hospital laboratory".

I guess what I'm again trying to say is that INR was supposed to eliminate these variations, allowing for a direct comparison between readings taken anyplace that reports them as an International Normalized Ratio (INR). If you correct INR for the difference in ISI, you will be putting yourself in a very dangerous position. It is the clotting time that is different, not the INR result. I suggest you call again and ask to speak to the technical supervisor and get this clarified to your satisfaction. Stop chasing results, trying to match them from lab to lab. Either trust the ProTime or Coagucheck, whichever you use or get rid of them and just go the the lab. Its not worth the stress sweating variations that are probably more attributable to lab technique, sample handling and diet/exercise variations.

Sorry if this is rather long. I just shudder to think that others may be adjusting their readings based upon your e-mails and then changing their Coumadin doses to try and get everything to match.

[allodwick]

We can't dispute that Evelyn is giving the true information that Lakeesha gave her. However, I don't think that Lakeesha is giving correct information. When she says that the CoaguChek has an ISI of around 2 -- she is showing that she is not giving factual information. The ISI of CoaguChek is 2.0 and has been for the past 5+ years that I have been using it. Therefore, I would mistrust anything else that she said.

Would somebody call her and pin her down on what peer-reviewed medical journal this 0.666 factor was published in. Get the year, volume, page number and author. Otherwise you can just put this down to a sales person trying to fluff their own product while dissing a competetor. No more believable than a used car salesman saying that it was only driven to church on Sunday by a little old lady.

[QAS]

I do believe that Lekeesha was merely stating that from lab to lab, monitor to monitor, etc., a .666 difference is the allowable mean. She is not a salesperson, but a technical support assistant for ITC. Her number is listed in the previous posts, for those of you who would like further clarification. From what I've learned, an ISI of 1.0 is recommended by the American Heart Association (AHA), the College of American Pathologist (CAP), and the World Health Organization (WHO). The majority of the time, when a laboratory is performing a correlation study, one of the strongest selling points is the ISI 1.0. I cannot argue the accuracy of the CoaguChek, as we all know both monitors are found to be very acceptable monitoring tools, but I can share the benefits of the ProTime Monitor. Feel free to call any of us at QAS, and we will do our best to justify all of the benefits of our instrument.

Lance

[allodwick]

I agree with Lance. There are hundreds of thousands of both instruments in use with good results.

This is exactly what I hoped someone from QAS would write. You cannot just add or subtract a factor that will apply to every one of these instruments.

[Hank]

Ok Folks - All things being equal - or not equal, what we are really concerned with is monitoring our INR's at home without having to go to a stupid lab every 2 weeks or every month or whatever.

I personally don't concern myself with any possible differences between the machines. You are never going to be able to keep your INR in a 0.666 range anyway.

For my valve (mechanical St. Jude in aortic position), the AHA recommends an INR of 2.5 to 3.5. I personally would rather have it 2.5 - 4.0. (better to bleed than clot theory).

I use my ProTime to monitor trends and drastic changes in my INR. I wouldn't be able to fine tune it to a .6 tolerance anyway. My diet and inconsistent life would make that impossible.

My point is this: The home monitoring machine should be used to establish a personal baseline (norm) and then used to identify trends and such.

I hope I am making some sense here. But probably not.

Anyway - Let the controversy continue so we can continue to learn from the debate :D

[Granbonny]

I was beginning to get swimmy headed from all the Tech. talk..I just worry more about getting my blood to flow..so I don't ruin a cuvette.:D I'm trying to live a normal:p life rather than worrying about my INR every hour, every day...I really think my Clinical nurse thinks I take it too often..every 2 weeks..but she is so sweet and always calls back and say..stay on same dosage and test again 3-4 weeks. Bonnie

[Ross]

I'm trying to live a normal life.
You can't do that if you talk to me! I ain't normal and you know it. :D

[Granbonny]

Posted by LA Cruiser reminds me of me and you..:D :D We need a life Your Therapist

[EVELYN]

I said to myself that I would not deal with this issue on this list as I do not need to be flogged and burned at the stake again, but I have since donned my armor and my flame-retardant suit and will post exactly what I was told from Dr. Marcia L. Zucker, Director of Clinical Research at ITC, 800 631-5945, extension 213, mlzucker@itcmed.com.

Dr. Zucker contacted me, at Blanche's request, to clear up the problem she perceived I was having with the INR rates between different labs/coagucheck machines in comparison to the Protime. She said that they, "frequently see differences between labs and point of care systems." and with the Protime machine the "difference can be up to .6666, but that does not mean that everyone will always see a difference every time."

She also went on to say that the "plug has no effect on INR results, just converts the values of the ISI from 1 to 2."--which I knew.

She continued to say that Lakeesha was correct in what she told me and said that I was like a "breath of fresh air," in that I realized poc systems and labs can and do have differences and as long as you're within the variables it's ok.

I like our Protime and trust it completely. I'm also very satisfied with the explanations received from Lakeesha and Dr. Zucker. I know that there can, may, might, and probably will be a difference of up to .6666 in comparison tests, and I'm NOT going to worry about it any more, so knock yourselves out burning and flogging.

Evelyn

[allodwick]

Evelyn,

You are a true scientist. You are to be commended on your quest for truth. This is a well-written explanation of the "problem" with various methods of testing.

Flogging and burning ... remember the Church condemned Galileo to eternal Hell for saying that the earth went around the sun.

This problem with testing has plagued warfarin since it was first brought on the market. Prior to the INR system coming into use about 1990 the testing system was much more crude and there was no way to know what the actual reading was even from day to day in the same lab.

I know one person who worked in a hospital lab about 20 years ago. Every morning a person went to the lab and had a protime done. That person's blood was the standard for the day. Then everyone else who had a protime that day had their warfarin adjusted to try to keep their protime between 1.5 and 2.5 times what this "control" protime was. What they did not realize was that some of the testing material was fairly insensitive. (Today we would say that it had a high ISI.) This resulted an 1.5 times control corresponding to an INR of approximately 8 !!! No wonder people bled and there were all sorts of horror stories about warfarin.

Again, you are to be commended on your quest for truth and clarification. As we all know there are very few absolutes in medicine. We are all on a continual quest for what works best. Thanks for your very valuable contribution to all of our knowledge.

[JimL]

Al, I thought Galileo got it right, "It [the earth] does move." ONE church, anyway, condemned him, along with a lot of other people.

Not to add confusion to an issue, but rather to confess my ignorance: Somewhere I heard that there are various kinds of tests, all called prothrombin, PT. Then for each test there is a conversion factor to turn the PT into an INR number. Theoretically, the INR should be the same for all kinds of tests, while the PT would theoretically be different for all kinds of tests. There, I think I've confessed enough ignorance that someone will surely correct me and educate me. Perhaps the answer is that even with all the theory, there still practically are differences in the INR readings.

[allodwick]

I edited the earth-sun thing and I think I got it right. Maybe I will only have a short stay in Purgatory!!

You are correct that the INR is a mathematical realtionship between the Pro time, and the sensitivity of the material used to run the test (ISI). Because the formula uses the ISI as an exponent, it works best when the ISI is 1.0.

The INR is accurate to compare different results, but because some materials (CoaguChek is an example) have an ISI higher than 1.0, the INR beging to become less meaningful the higher it gets. It is very useful for comparing results near the desired ranges.

It is true that the Pro Time is more accurate because it has an ISI of 1.0. However, this is not rocket science - we are not calculating the amount of fuel we need to get to the moon and back. An ISI of 2.0 is perfectly acceptable for INRs up to about 5.
If the person's INR gets above 5.0, you need to make an adjustment whatever the ISI.

The way that I treat patients above 5.0 is to hold a dose or two of warfarin if they are not bleeding. If they are bleeding then steps need to be taken to control the bleeding. So, while it might be nice to know whether the INR was 5.1 or 5.2 from a scientific standpoint, for reality it doesn't matter to me.

To use a car analogy, the speed limit is 35 and you are pulled over for speeding. Is it going to make any difference whether you were doing 51 or 52????

[Zipper]

Hi Al,

I hear what you are saying and stayed out of this dicussion until now. Quite some time back, when I received my ProTime unit, I posted that I did a three way test with my Lab at the hospital I work at. The first thing my Lab tech checked is the ISI, and told me the compatability of calibrations.. Then we did a three way test. The venous draw was used to be analyzed by the Lab and drops from same used in the curvette. At the same time we did a finger stick....Now I forget the exact #'s...it's in the archives...but I do know they all were 2.something which was quite to the satisfaction of my Lab, my Cardio, and therefore myself. As it's been so controversial here lately, I hesitated to reiterate my findings.

This is why I personally am very confident with home testing altho I still visit my Lab every so often since my insurance denied payment, citing it to be a 'medical device' not of necessity to patient. BTW...to my understanding...this is the stand Medicare is taking also. I posted regarding that as well.

Thank You for clarifying this ISI issue!!!

Zipper

[allodwick]

Just when we think that we have that nailed down, along comes a new gunslinger who wants to make a name by knocking off the top gun.

In the November 2002 issue of Pharmacotherapy, Shermock et al (shermok@ccf.org) of the Cleveland Clinic published an article titled, "Differences in warfarin dosing decisions based on international normalized ratio measurements with two point-of-care testing devices and a reference laboratory measurement.

Their finding was that the AvoSure device produced a reading that resulted in making the same decision as the reference lab reading regarding a warfarin dose 78% of the time. The ProTime device gave a reading that resulted in making the same warfarin dose decision as the reference lab reading only 66% of the time. This was mainly because the ProTime overestimated low INR values more often.

[Zipper]

Geez...on it goes....let's not forget that with venous draws the techniques of the lab techs can also produce varied results! It certainly is NOT an exact science..but nothing in medicine is! Thanks for the info, Al.

Zipper *~*

[KIRSONRON]

Could you please define "overestimated low INR readings"? Does that mean that Protime's INR readings were somewhat lower than a reference lab or that the INR readings came in on the high side?

[allodwick]

I just quoted what the article said. I take it to mean that the ProTime gave a higher number than the reference lab when the INR was on the low side.

I didn't want to mix my opinion with the statements in the article but now that they are separated, I will give my opinion. Overestimating a low INR is a serious situation. You are much more likely to suffer serious consequences from a low INR than a high one. A low INR can lead to a damaged valve or a stroke. A high INR most often results in only a bloody nose, or possibly blood from the bowel or bladder. Serious bleeding is fairly rare.

[KIRSONRON]

I was asking because the Protime readings I get are somewhat lower than the quarterly lab readings taken during the same time period.

[Granbonny]

If you are still around forum please tell me an OTC cough syrup..I broke into a hacking cough after I went to bed. Not having anything to take or knowing what to take scared me..A glass of water cleared it up..but would like to have something on hand that would not interfere with my INR..Thanks, Bonnie

[allodwick]

Anyone who was at the Las Vegas Reunion will think that I am an expert on coughing NOT on what stops coughing!!!!!!!

I recommend Robitussin &/or Robitussin DM -- the generic equivalents.

[QAS]

If anyone would like a current study, done by muliple centers, please call Lance at 800-298-4515 ex 2865 and I'd be glad to send it to you. The study is from the American Society of Clinical Pathologits and they used the ProTime Monitor, a hospital laboratory and a reference lab. The findings, done on some 386 subjects, will answer some of your questions regarding accuracy of the device vs. laboratory. I think you will have some additional peace of mind upon review. Let me know if anyone is interested, or would like to share this study with their Dr's.

Lance

[allodwick]

You guys at QAS are doing good work. As we all know, there is no one easy answer. Building up a body of evidence like this is all we have to go on in keeping up and trying to make the best decisions. It is very rare that one study is definitive about anything in medicine. What you have to look for is the preponderance of evidence.

[Zipper]

Compliments to you as well as QAS..you help us all so much with informed replies and general information. We're all lucky to have you and QAS looking out for us and our best interests. I continue to learn and it's much appreciated.

Zipper *~*

PS...AND of course...HANK...big thanks for this site. All you guys are really great!!!!

Zip *~*