Just to toss my .02 in, INR won't vary between labs, hence the "International Normalized" part. PT and PTT can vary quite a bit depending on what lab and where, the INR won't. (or shouldn't). That's why they use it, but still we get the PT tossed in there for posterity. Both will go up and down in unison. INR readings of 1 are average joe/jane, 2 would be blood that is twice as thin, 3 is 3 times, so on so forth.
RRMS Dx'd 2007, first episode 2004. Bilateral stent placement, 3 on left, 1 stent on right, at Stanford August 2009. Watch my operation video: http://www.youtube.com/watch?v=cwc6QlLVtko
, Virtually symptom free since, no relap