My daughter has had to have B12 injections twice within a year. Blood test for GPC antibodies came back as negative. B12 3 months after injections is 253ng/L (180 - 900). Serum folate 22 range 4.0 - 20. She has been supplementing folic acid which will explain high reading. Should she take sub lingual B12 in the hope it raises her level? Or do we wait for another blood test to see if it drops further. She is suffering with extreme tiredness and can't stay awake.