Vitamins & minerals
Vitamin B12
LOINC 2132-9 · ng/L
Ranges
Reference range: 200–900 ng/L
What it is
Vitamin B12 is essential for nerve function, DNA and forming healthy red blood cells. The body stores it, so deficiency builds slowly.
Why it matters
It is key for energy, the nervous system and preventing a specific type of anemia.
What high values can mean
A higher value usually reflects supplements and is generally not a concern.
What low values can mean
A lower value can cause tiredness, tingling and anemia, and is more common with plant-based diets, older age or absorption problems.
How to improve it
Animal foods or fortified foods and, when advised, supplements or injections correct a deficiency.
Food & lifestyle
Meat, fish, eggs and dairy supply B12; people on plant-based diets should use fortified foods or supplements.
Preparing for the test
A blood test; fasting is not required — follow your lab's instructions.
When to talk to a doctor
Discuss low B12 with a doctor, especially with tingling, numbness or balance problems.
Related markers
Sources
- MedlinePlus (NIH)
- NIH Office of Dietary Supplements
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
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