Hemoglobinopathies (like thalassemias) produce red-cells that have a shorter life-span than regular 'normal' red cells. So yes, there is a high turnover and therefore higher demand of nutrients. However, there are other explanations as well. If you like further exploration I would suggest you make a new thread? Results from the last 4 years would give a tremendous head start.
Can alpha thalassemias present with normal hemoglobin, but chronically low ferritin? My hematologist suggested my hemoglobin was normal because I burn through ferritin so quickly. Like OP, my specialists have all but thrown in the towel after four years of treatments (for a diagnosis that has now been thrown out - Von Willebrands 2M).I have had high RBC and low MCV, normal HCT and HGB, low B12 and D (take weekly injection of the former, high dose oral supplement of the latter). Ive had two iron transfusions ~4 years ago. I can provide complete blood work for the last four years if that would help.