Vitamin B12
Also known as: B12, Cobalamin
Vitamin B12 is a nutrient important for healthy nerve function and the formation of red blood cells. Your body gets it from food, mainly animal products, or from supplements.
Why it's measured
B12 may be checked when looking at energy, nerve symptoms, certain types of anemia, or nutritional status, particularly in people whose diet or absorption may affect their levels.
Typical range
Labs report B12 in pg/mL and flag values below a threshold as low. Ranges vary, and your doctor interprets borderline results alongside your symptoms and other tests.
What high values can mean
Higher B12 is often related to supplements and is usually not a concern on its own, though your doctor may note context.
What low values can mean
Lower B12 is a finding your doctor may explore further, sometimes with additional testing, depending on your diet, symptoms, and history.
Questions to ask your doctor
- Is my B12 level something to act on?
- Could my diet or any medications be affecting it?
- Do you recommend any follow-up testing?
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Try the explainerEducational information only — not medical advice, diagnosis, or treatment. Reference ranges vary by lab; always use your own lab's range and discuss results with a qualified clinician.