My teenage relative was given six loading doses of B12 after their level tested at 136. Iron levels were low normal folate normal blood count etc normal.
Three months after loading doses b12 levels were 288. Intrinsic factor anti body was not tested for as Gastric Parietal Cell antibody was negative.
Symptoms are tiredness inability to concentrate mood swings also excessive sweating forehead/back I don't know if that is related.
GP considers the case closed.