Iron will fix general Iron Deficiency anemia, but not PA for example; it has to be treated with B-12. You become anemic for different reasons, as you know, but it is all treated the same. Many doctors will not run further tests for B-12 because they say it's still treated the same way. I think they should always find a root cause. It helps to know more about your medical state. Whether your have an autoimmune disease process at work or what. Having one puts you at greater risk for others in the future. This is why you have to have so many different test to find a cause. You can have both IDA and B-12 deficiency at the same time (very common), for many different (malabsoprtion syndrome) reasons. B-12 can only treat B-12 and iron for iron def. If you have both you need to treat both. I will give you an example, for myself, I take PPI's that can cause some malabsorption. It can change your B-12 intake and iron. For me it only causes iron malabsorption, my B-12 is great. I still supplement with B-12 so that I don't end up with a problem because this puts me at a higher risk. Other people that take PPI's may malabsorb both or just B-12. It depends on your own body and what is going on. I also have Hashimoto's Thyroiditis, this too can cause reduced stomach acid needed to absorb iron, so who really knows what's going on. Only testing will tell. FLFLOWERGIRL