Just to add more confusion i have contacted a Consultant Neurologist Professor who explained does not follow guidelines i'm sure that means only treating the symptoms for B12 . Also explains, If you get a year of B12 injections monthly, you have probably had enough B12 for the rest of your life.
You saturate with B12, with several injections over a few weeks, and then less frequent injections indefinitely. Each doctor has their own way of doing it.
Also guidelines are really for doctors not for patients. Discuss it with your doctor, and if you are not satisfied with the way he is treating you, find somebody else. He explains my B12 levels have always been within the normal range from the figures i provided
ie 155ng/L 145ng/L ? (Range 130-800)