- Increased - Macrocytic
- Decreased: - Malnutrition, Cancer, Psoriasis, Hemolytic Anemia, Megaloblastic anemia, Malabsorption
- B12 deficiency: 140-700 pg/mL - Increased: Leukemia, Polycythemia vera; - Decreased: Pernicious anemia, Malabsorption, Pregnancy