I have been on Coumadin (warafin) for many years. Blood goes too thick & too thin. had blood work done at St. Michaels in Toronto, and the head of hematology who also teaches, could find NO cause. Recently, a growth was detected on the left kidney. My Dr. took me off of coumadin, put me on Xarelto (15mg daily). I stayed on that for maybe a month, had blood work done. He took me off of it and back on Coumadin. Then back on Xarelto. Is this common practice, or am I a guinnea pig?? the last time on Coumadin, I had blood work done daily for 8 days, when he got the reading he would advise the doseage. I need a second opinion here. Thank you for your help. I am female, 78 yrs. old. Have had multiple strokes but nothing paralyzing, TG.