Testing just the TSH is one of the problems - it is a Pituitary hormone and being told its normal is an opinion rather than a result
Research goals: Longevity & Anti-Aging, Metabolic & Weight Description 5-Amino-1MQ (5-amino-1-methylquinolinium iodide) is a small-molecule, membrane-permeable inhibitor of nicotinamide N-methyltransferase (NNMT), the enzyme that converts nicotinamide and S-adenosyl-l-methionine (SAM) into 1-methylnicotinamide and S-adenosyl-l-homocysteine
Clinical laboratories generally define vitamin B12 deficiency as a serum level below 148 pmol/L (approximately 200 pg/mL)
The choice between subcutaneous and intramuscular administration may depend on the formulation, the patients body composition, and the clinics experience
People may have low B12 levels if they are on a vegetarian or vegan diet
This could be daily, weekly, monthly, or at other intervals appropriate for your physiology