warfarin taken for anti coagulant effect should produce readings between 2.and 3 on the inr scale.?

Question

why should readings increase from 1.9 to 4..1 in 2 wks.when no vaccine, anti biotics, or illness was a factor ?Diet was stable

Answer 1

Major things that affect INR: salycilates (aspirin), barbiturates, oral contraceptives. OTC meds can change the INR. Diet or vitamin changes which decrease the intake of vitamin K can affect the INR. Another thought is blood dyscrasias which requires getting d-dimer and other bleeding profile studies done. Another thought is liver function. If liver function is down then PT/INR goes up. LFTs can determine liver function and is a blood test. Hope this helps...

Answer 2

The numbers your want your INR (which is how we measure how well the coumadin or warfarin is working) to be between varies slightly depending on the reason for taking it, but most of the time it is between 2 and 3 (it is between 2.5 and 3.5 for prosthetic valves).
As for why the levels change, many changes in diet, lifestyle, or medications can cause that, or it may be, if you started taking it recently, that they just haven't found your dose yet, sometimes it takes a few days for the level to equalize even if the dose is kept the same (it has a long half life, so you can't really tell what INR a given dose will leave you at for several days after changing the dose).
Some common foods that can alter INR are green, leafy vegetables, which contain vitamin K and can counteract the effect of the drug, and cranberry juice. Aspirin is a very common medicine which can raise INR. Your doctor can give you a complete list of the things that affect it, but if you've been on a stable dose for a while, take a look back and see what changed, rarely will the INR go out of control once it's stable without a reason.