Iron Infusion = Dosage Increase?

[Elcarim]

I've been on warfarin for 18 years for my artificial aortic valve, and in that time I have always taken a similar dosage to stay in range at 2.5-3.5. I would do a three day rotation of 4 4 3 or 4 3 3 (mg) and my INR has been pretty stable for years.

Recently I was found to be deficient in iron, so my GP arranged for me to have an infusion. In the eight weeks since the infusion I have had to increase my warfarin dose to 4 5 5 to stay in range. My last INR was 2.7 so I may need to go higher again after my next check. Nothing else has changed in my lifestyle or medications other than that I now have healthy iron stores and my hemoglobin is slowly creeping up.

It is possible that I was iron deficient for decades before the infusion, I was told I was low in iron during my first pregnancy 20 years ago and I didn't have the best nutrition growing up, so this could be the first time in my adult life that I have good iron levels. My ferritin was 19 before the infusion, it is now about 250. Would this increase in ferritin cause my INR to drop, thus requiring a higher dose of warfarin to stay in range?

 

[LondonAndy]

I don't know if low ferritin would cause a need to increase your warfarin dose, but just wanted to mention: in some of us with artificial valves it is the valve itself that is damaging the red blood cells, thereby causing the low iron level. The action of the valves opening and closing physically damages them. I was diagnosed with normocytic normochromic anaemia a few months after surgery in 2014, and have been on Ferrous Fumarate tablets ever since. I don't think the following is necessarily relevant, since we all need different warfarin doses, but my dose is typically 6mg/day.