I wonder if anyone can offer any advice, my mother has just returned from the doctors with an INR level of 8 could possibly be higher the machine only reads up to 8! On Friday it was only 4.6. She has had vitamin K administered by mouth to bring the levels down but is due a cardioversion this Friday. Does anybody know what INR levels have to be to have this procedure done? she's also got a mechanical mitral valve and I've read that vitamin K should be taken with caution in people with these. In advance, Thank you for your time and help.