Red cells large 5 yrs after correction of b12 def. with high erythroproiten level. further testing?

Yes: There are many things that can cause elevated red blood cell size-besides vit B12 deficiency. To name some of them will include thyroid problems, other deficiency, bone marrow failure, liver problems, drugs related, breaking down of red blood cells etc. Yes, you should have work-up done. Please go to see your doctor and get yourself checked.

See your MD: Anemia can be a very complicated diagnosis. Without a more detailed history and physical, it would be difficult to give you a precise answer. A high erythropoietin levelsuggest that your body is trying to make more red cells. Many disease processes can give you large rbcs, including B12 deficiency. Consider following up with your hematologist or pcp for more details.