Koch reported normal serum concentrations of vitamin B12 and raised gastrin levels ... Response of elevated methylmalonic acid to three dose levels of oral cobalamin in older adults.

Methylmalonic acid levels are normally low in healthy individuals. Elevated levels have been linked to aging and vitamin B12 ...

A vitamin B12 blood test is one way to know if you’re B12 deficient. Some people opt for a urine test instead. Learn when ...