Originally Posted by huzar
You'll also want to get a genetic test done for variations in CYP2C9 and VKORC1. About 30% of the population has a mutation that makes them either very rapid metabolizers of coumadin, so the drug never reaches effective levels, or slow metabolizers, so the drug builds up to toxic levels in the body. Most insurance programs will cover such a test now.
A little overview: http://emedicine.medscape.com/article/1733331-overview
Marcin, is there anything you DON'T know?