when first tested the reading was serum vit 12 70 ng/l
now after many many b12 injections plus b12 spray the reading is 1000 ng/l. is this good/good enough?. I am seeing my very difficult gp next week and need to be sure of my facts. grateful for advice as always.
Your blood level of B12 of course looks good as you have been injecting. However B12 is needed in the cells not in the blood. I have read here that the Guidelines on Folate and B12 Deficiency published by the British Haematological Society mention that testing B12 whilst supplementing is not useful. It is not the full picture.
Please read the two Pinned Posts to the right of this post - so much useful information for you. Possibly difficult if you are on a phone 
Others - more experienced than me will be along soon to assist you with good advice.
Hope all goes well with your difficult GP. Just be assertive and polite ......
What Marz said, check out the Pinned Posts.
The 1000 does not say anything about the efficiency of the treatment. Might even be that the lab doen't test higher, but it does not matter. There is, or should be, only one way of telling if you have enough B12 and that is if the symptoms stay away (or are at least stable, depending on situation)
Those levels should be high enough. If you're not suffering from symptoms of B12 deficiency (look in the pinned posts) then the important thing is to keep them up there. Don't let your difficult GP tell you that you don't need any more injections because your levels are OK. (Would they stop a diabetic's insulin because their blood glucose if 'OK' this morning?)
If your initial low levels were due to a temporary cause (veganism, some drugs such as PPIs or metformin) then you'll need injections for life.
My summary document - frankhollis.com/temp/Summar... - contains links to useful documents and extracts of the more important bits.
many thanks
See bottom of page 4 of latest BMJ research document:
"How is response to treatment assessed?
"Homocysteine or methylmalonic acid should normalise during the first week of treatment. Failure to do so suggests an incorrect diagnosis, unless renal failure or other causes of increases in the metabolites coexist. Cobalamin and holotranscobalamin levels are not helpful because they increase with vitamin B12 influx regardless of the effectiveness of treatment,24 and retesting is not required."
cmim.org/pdf2014/funcion.ph... :
....................
stichtingb12tekort.nl/weten...
Under 'Misconceptions about B12 Treatment - 5 and 6
Confused .com. 
Results MMA & Homocysteine
B12 Level falling 
