Hi this calculator is quite easy to follow and you don't need to sign up to anything, and I think is more accurate than a doctor guessing a dose every month,
as from what I've seen so far doctors do dosing off the cuff rather than having some sort of reasoning deduced from data
http://www.globalrph.com/warf-maint.htm
So far I've found warfarin dosing is a bit of an art but becomes easier once you start have some records and data to follow, then it becomes just another thing, ( and help from fellow members... thanks)
I do weekly testing both myself with a coaguchek and at a hospital lab which also use a coaguchek meter
My INR so far has alternated a fair bit , and I can see that if I did monthly testing I could be a long way out in between which is a worry
My father is also on warfarin with a mechanical AVR and has only done monthly testing with an arm blood draw, and he's done that for 30+ years and his veins aren't flash,
he's also had a clot (14 years ago) due to doctor dosing incompetence. But it has worked for him
I had a blood draw (first since surgery) 2 weeks ago for a cholesterol test and I thought OMG thank the stars for finger prick testing