I have 2 mechanical heart valves fitted and have been taking Warfarin since May 2013 I am a 46 yo male, my range is 3-4, target 3.5 I have been taking anything between 9-14mg of Warfarin since then (dependent on INR results) and am presently taking 13mg daily. Since May my INR has been up and down like a yo yo ranging from 1.9 - 3.9 I have very rarely been above 3.2 or thereabouts generally around 2.5. Yesterday I received an alarming call from KCH Warfarin clinic telling me my INR had dropped to 1.0 and that I was to come in and receive some blood thining drugs as I was in great danger of sustaining a heart attack, I went and received the treatment and was given injection to go home with. Having asked the question why has my INR dropped so low, I get the usual it could be a zillion and one things, however the only thing I did differently in my life over the weekend was to take a run in the park and sit in the sun, both of these things are a rarity in my life and not something I'd normally do so therefore can only assume this is why my INR had dropped to a very dangerous level..............but why would this be, I assumed that exercise and sunshine would be beneficial to me. I've had minor scares before but this was the worst result I'd ever had and therefore I am so worried about anything I now do.