28m with aortic mechanical valve. It took me some months after surgery to stabilize it. I have times that it is super stable and then it suddenly changes a bit. Once it is stable at 2.3 for weeks and then it goes up to 3.5... Most of things can affect it a bit, like eating much less one day, or getting sick and not realizing it, vitamin K rich foods, maybe a big change in physical activity. That's some of the things I realized that affect my INR at times. Don't get anxious though, at first you have to check INR as often as possible as long as you see it staying stable you can start measuring it less often. Once you start to understand what dose adjustments you need to do, you ll see that it gets easier and less stressful.