warfarin blood tests at the beginning -- how frequent?

Those of you who are knowledgeable about warfarin/coumadin: when people first start taking this, how frequently does your health care system require blood tests? i'm starting coumadin literally today after doing a lot of research and consults. the treatment is managed by an anti-coagulant unit, labs and results and adjusting the dose. everything i learned about this spoke of weekly blood tests until the inr/ptt stabilized, then longer periods between. . NOW the anti-coag unit says testing is required 2x a week probably for months. Problem is, labwork requires a high copay each time. 8 x per month is unaffordable. So what is the protocol where people here get warfarin monitoring and dose adjustment -- in the beginning? many thanks to everyone here for sharing your knowledge and experience.

42 Replies

  • My surgery in UK uses a Coaguchek machine . A finger prick provides the sample which is read by the machine and a printout with dose and date of next test is provided. The dose is generated by sophisticated software but if the care asst. thinks it necessary will discuss with GP. Nowadays the protocol for starting warfarin ( coumadin) is to start slowly so it does take a bit longer to reach the required INR. I started on weekly tests but these quickly became fortnightly and now unless meds change it is every 10 weeks.

  • So at the beginning you started on weekly tests, right? That's what I've always heard. My clinic uses coagucheck after 3 months.

  • Yes that's right. My husband and I both on warfarin and Coaguchek from day one. Strange how everyone different. Our only problem is that our surgery is not connected to hospital computer system so when I had surgery had to have a venous blood check there as results had to be " put on the system". Husband however did not!! Different nurseI guess

  • Can you get yourself a Coaguchek monitor? Then you can test as often as you like. Most people test once a week and I'd have thought twice a week is not necessary, even initially. They're a bit behind the times if they're still using expensive labwork.

  • coagucheck available from the clinic after 3 months if inr is already stable, and if you 'pass' their instruction course and show you can use the device correctly.

  • My experience is exactly as that of Bagrat and it works very well for me. I think each patient has to be treated as an individual, so others will have a

    different experience with Warfarin. You should take the advice of your medical team.

  • thanks, but if i take the advice of the anti-coag unit, 2 x a week labs will cost me almost $300 a month--for god knows how long -- just for blood tests. who can afford that?

  • The cost of testing INR may be a factor in your decision as to whether to choose a NOAC instead. There is a huge variation in how easy it may be to achieve control on warfarin, but 8 times in 4 weeks sounds unlikely to be necessary

  • i mentioned i already took eliquis for a month. didnt absorb. i had a gastric bypass 19 years ago, the NOAC trials excluded subjects with intestinal surgery so nobody knows how post-bypass patients will benefit --or not-- from the NOACS, the researchers and med people recommend coumadin, i took eliquis anyway, but it's too risky if there is no protection. however -- no place recommends initial testing at 2x weekly, as far as i can see.

  • As Goldie has suggested maybe one of the new oral anticoagulants may be more suitable for you. The problem is that warfarin is not universally metabolised the same by everyone. In the early stages it may be difficult to get you into range depending on the methodology used. When I started warfain 14 years ago I was given a high loading dose and tested after two days. The results then dictated the next dose and so on until after about three weeks I reached stasis since which time I generally go every two months or so. BUT in this company I seem to be unusual and some members never seem to reach a stable level and need constant adjustments to dose and regular testing. I note that most newer members find that their clinic tend to creep up on their INR with tiny increments and lots of testing so you may find that is what is planned.

  • I do not have to hand some of the more recent journal articles on this. BobD you are correct, that the modern way is to start with a small dose and creep upwards. This method is much safer than the old method of starting high with two loading doses, and research somewhere has shown that the two methods arrive at the same endpoint at a similar time. Therefore take the safer method.

  • i had a gastric bypass 19 year ago i posted about this a couple of weeks ago. i took eliquis for 1 month, it didnt absorb. warfarin is measurable, so i had to switch.

  • Testing twice a week for months, for most people, is totally un-necessary. In fact, it could be counterproductive. Too frequent testing means people are tempted to intervene prematurely, and not allow for the nature to take its course and swing back into balance naturally. ,

    But, I with a science background, would be fascinated to see your INR results, tracked twice a week for several months!! Could it be that they are simply collecting data?

    I know this is difficult to do, even for someone with a science background, but, every patient has the right to ask a doctor to give their reasons for a decision. The trick for the patient is to formulate the best questions. Remember, knowledge is power. A question can be said in an innocent non-threatening way. Try these:

    1. Please show me an official document (journal, guidelines, hospital policy etc) which says I should test twice weekly.

    2. I have heard that after the first two weeks, then tests every 1-2 weeks are more usual. Why are you going against this?

    3. Frankly, I am not worried about an INR above three. Any result up to five is fine. As long as the INR is above two I have my protection. So why the need for more frequent testing?

    If I get a minute later, I may try to track down some more relaxed guidelines you can show them.

  • exactly what you said is what i got from the research. 2x week is too much intervention, 1x weekly is the norm til it stabilises. Nothing in writing says 2 is required they instruct by phone and email. i had a long argument with anti-coag unit person, then with member services, then contacted my cardio but will hear nothing til monday. my objection is financial. $300/month for ongoing labs makes the medication unaffordable.

  • Here is just one reference. I am sure more recent references confirm this.

    For outpatients who do not require rapid anticoagulation

    a slow-loading regimen is safe and achieves therapeutic anticoagulation in the majority of patients within 3–4 weeks (2C).

    From: Guidelines on oral anticoagulation with warfarin – fourth edition 2011.

  • clotcare.com/ptinr.aspx

    Might help explain it? One thing I will say that certain foods will affect it so take that into effect? However as a Warfarin taker since 1992 if you eat roughly a consistent diet then the INR/warfarin will be sorted in the end to meet your lifestyle.

    Be Well

  • They use a finger prick test on me and I go every week here in U.K. Very quick and easy , just a pain if you work .

  • here the lab does a regular blood draw from a vein, coagucheck available after 3 months.

  • My nurse just pricks my finger, allows a little blood to flow onto a special strip of card, which is plugged into a small machine. About two minutes later the machine gives an INR reading, which is entered on her computer which then produces my new dosage.

  • thanks. how often did you have to get checked at the very beginning, starting out?

  • There are self-testing systems using Coaguchek meters in the USA. See coaguchek-usa.com/coaguchek.... I bought my own Coaguchek meter in the UK, for piece of mind. Initially my INR would not settle. I was put on a NOAC, but I had an adverse reaction to it, so requested to be put back on Warfarin. Having spent £299 for the meter, I found my INR suddenly stabilised. I send my readings by email to the Cardiology nurse when required. Recently I changed my daily diet to lose weight and my dose was adjusted. It took weekly tests over a 4-week period to stabilise.

  • thanks. my question to all is: when FIRST prescribed warfarin how often did you have to get a blood test? At first. after that i understand the inr can change for many reasons. im in northern california covered by medicare and kaiser medicare advantage. they provide a coagucheck after three months stable. i started taking coumadin last night, first time ever. tool eliquis one month, it didnt absorb.

  • How long? It varies. It was several months before I was taken off warfarin and put on a NOAC because my INR wouldn't stabilise and because I had a painful rash on both fore-arms, (the rash was the result of another medecine). Due to adverse reactions I was taken off the NOAC after 12 days. I bought a Coaguchek meter and went back on Warfarin. My INR stabilised in a couple of weeks.

  • Hi when I started warfarin I had to go weekly until I reached a constant level 2.5 / 3.00....approx 6 weeks,now approx every 6-8 weeks

    Hope this helps

  • yes, thanks, it does. it seems the common practice to begin with for most places is weekly.

  • It depends now how brave you are. You could, without a prescription I think, just invest in a coaguchek meter, and do it all yourself: self testing and self dosing. All you need a prescription for is the warfarin, and any doctor should be able to prescribe that.

    Probably most people self test and self dose once the initial 3 months is over. But it is not that difficult. You could compromise, and say you will go for an official checkup every week, or every two weeks, and self test in between. I hope you find someone who will listen to you. Another thing you might do is to ring around the local doctors and see who has the fingerprick test, and pay for that locally. Any doctor should be able to handle the initiation process, following the protocols is easy enough.

  • Thanks very much for the suggestions. i'll try them :-)

  • I just checked my original results on starting warfarin. 1st test was after 3 days, 2nd test after another 3 days then 3rd after a week, 4th after a week, then every 2 weeks as I had stabilised. A month later I got my own Coaguchek.

  • thank you! that is interesting and helpful.

  • Here's a slow start regime with weekly blood tests, which would be the norm in the UK. Why not ask for this?


  • wow! thanks very much for this. very, very helpful helpful. the clinic seems to be following a protocol very similar to this -- except for the timing of testing. they started me on 5 mg taken in the evening for 4 days. then 1rst blood test on 5th day in the morning, next step depending on the results. the link you sent is a great reference for discussing this with them.

  • I have been on warfarin since 2008. and after settling down I am now on bi monthly tests and steady at 2.5

  • Because I've got a PE and a blood clot in my leg and it's my 2nd clot so I have to stay on it for the rest of my life but I'm ok with that!

  • Once your INR stabilises the norm is a blood test once per month with Warfarin. This is controlled by uhnm at Stoke.

  • I have been on Warfarin for nearly three years, for first couple of months was checked weekly, then went to four weekly then went to twelve weekly. I recently had to have an emergency operation and had to have an antidote to neutralise warfarin before the op. After operation I went back to weekly checks but am now on four weekly again , it depends on well your inr level stabilises .

  • Hi I've been on warfarin for 4 months now! At first I had my inr check 3 times a week, then it went too 2 times a week after 2 months of being on it, now I'm on weekly tests as my inr won't stabilise! Hopefully soon I can go onto fortnightly! Hope this helps you!

  • thanks! that's what they are doing with me. pain in the ass. hopefully they et it to stabilize.

  • Mine never stabilised always too high/ low after attending clinics all over my area and a day at hospital in Greece on hol, I asked to go on NOAC. Not looked back

  • i started on Apixaban for a month-- didnt absorb, ive had gastric bypass and NOACs havent been tested for people with intestinal surgery, only drug that works is coumadin. believe me ...i would prefer a NOAC for many reasons -(

  • Hi Psage,I'm on warfarin and have been for the last 30 years. When I first had to take it due to a D.V.T in my ankle/calf, and in hospital, there was a need for blood tests I.N.R's to be taken every day because whilst body is getting used to absorbing the warfarin its difficult to get exact doses right. I left hospital on first ever blood clot, taking 10mg nightly, and in the first fortnight being tested x2 weekly. Warfarin is a very unpredictable drug and reacts to lots of food/drink substances, which your health care professional should tell you about. When the I.N.R results have a consistent pattern to them and a target range is met, then your tests could start to become less frequent. The longest I have been is 10weeks..

  • thanks!

  • I am on warfarin and been on it 8 years now. You are correct about testing for the first couple of weeks until you stabilize your INR which is a level you will have to maintain with a good diet concentrating on vitamin k i.e. Cale, spinach ect. I go in every 4 to 5 weeks depending on my levels. I was told to maintain it between 2. 0 and 3.0 3 being on the high level, which would be thinner blood. Good diet and weather you like it or not, exercise.

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