Verification with serum methylmalonic acid and/or serum homocysteine level may be necessary in asymptomatic patients with high-risk conditions, symptomatic patients with low-normal levels of vitamin B 12 (200 to 350 pg per mL), or symptomatic patients in whom vitamin B 12 deficiency is unlikely but must be excluded
Grant, R., Berg, J., Mestayer, R., Braidy, N., Bennett, J., Broom, S., & Watson, J
Signs and symptoms include (but are not limited to): You may be at risk of vitamin B12 deficiency if you fall into any of the aforementioned categories
Red blood cell formation: B12 helps create healthy red blood cells that carry oxygen throughout your body
So, just not getting anywhere
Injection Site Reactions: Mild pain, redness, or swelling at the injection site may occur, but these symptoms typically resolve quickly