Hi Clare,

Yes, some people have been shown to be deficient with B12 levels higher than that. It is not common, unless one has begun getting some B12 and that is being measured in the blood, but it does happen. Usual people who are elderly, but I know one who was shown deficient (with MMA) while well over 500, and she was in her 40s.

I will speculate that either you are benefitting from the B12 injections and experiencing temporary worsening of symptoms or you are sensitive to some other substance in the injected product.

Your fingernails may or may not benefit from more B12, but they do not diagnose or rule out B12 deficiency.

rose