Thank you for posting your query.
The normal range written in the lab report papers mention a value of 200-800 for normal vitamin B 12 level, as you have mentioned.
However, for the nervous system to function properly, it should be at least more than 450. So, your vitamin B 12 value is low, but not very low. Hence, you require treatment as advised by your neurologist
I hope it clarifies.
Wishing you good health,
Dr Sudhir Kumar MD DM (Neurology)
Senior Consultant Neurologist