I have low B12 and was tested multiple times for pernicious anemia, all came back negative. I have a very good diet and had an endoscopy for Coeliac disease which came back negative. My specialist has decided to request a barium follow through test to look at my upper intestines as that's where b12 is absorbed. I've had life long severe constipation which is treated with laxatives. Is it worth having this test done? I'm just wondering whether to give up and leave all this alone. I've already had an endoscopy at a different hospital and this found nothing, I don't know what else this test is going to achieve. I'm currently receiving injections but they're not happy keeping me on these for life when they can't see why I got low in the first place.