Increased red blood cell disrtibution width

Patient: Hi, i have frequent blood tests due to being on methotrexate (I have arthritis)and the past 4 months have been coming back with an increased red blood cell distribution width. This has increased every time. Although it gets flagged up as outside the normal range,it has never been picked up on and I have never asked but I am curious as to why it may be. My Hb is within normal limits and is at the higher end of the normal range despite a diet that should in theory make me anaemic. Apart from a slightly high WBC, the other components of the FBC are fine. Is this anything to be concerned about or even raise with my rheumatologist? Many thanks.

Doctor: High RDW means that there is a difference in the size of your red blood cells, possibly due to anemia or lack of vitamin b12 or folic acid.Since you have a chronic inflammatory disease such as Rheumatoid Arthritis, you might be starting to develop Anemia of Chronic disease which is very common in conditions like RA.I don’t want you to panic, certainly there is nothing of concern right now but follow up CBC to rule out anemia in the future might be needed. I wish you the best.