Normal vitamin B12 blood levels range between 110 and 1,500 picograms per milliliter or 81 and 1,107 picomoles per liter, depending on the type of test performed and the individual laboratory's standards, explains WebMD. The ranges provided are only meant to act as a guide and are not firm.
Doctors work with patients based on each individual's unique medical history and current health profile, according to WebMD. Some vitamin B12 blood test results that fall above or below the normal range outlined by the chosen laboratory are still considered normal, and these assessments are made at each doctor's discretion. People with high levels of B12 may suffer from liver disease or leukemia. Low B12 readings indicate a specific anemia or the presence of tapeworms.