Vitamin B12 blood test
Vitamin B12 (cobalamin)
In short
A typical adult vitamin B12 result is 200 to 800 pg/mL. A high B12 is most often from supplements, B12 shots or foods with added B12. If none of these apply, doctors may look at the liver and the blood count. Always read your result against the range printed on your own report.
A vitamin needed for healthy nerves and red blood cells.
The body needs vitamin B12, found in animal foods and foods with added B12, for nerves and red blood cells. Absorbing it takes stomach acid and intrinsic factor, a protein made in the stomach. A result near the low end may be checked with a follow-up test, methylmalonic acid (MMA).
Is my Vitamin B12 high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Adults | 200–800 | pg/mL |
| Adults | 148–590 | pmol/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your Vitamin B12 is high
A high B12 is most often from supplements, B12 shots or foods with added B12. If none of these apply, doctors may look at the liver and the blood count.
Common reasons
- Vitamin B12 supplements, multivitamins or energy drinks
- B12 shots in the weeks before the test
- Less often: liver disease or some blood and bone marrow disorders
If your Vitamin B12 is low
A low B12 can come from diet, from trouble absorbing it, or from some medicines. When the result is close to the cutoff, a follow-up MMA test can help confirm it.
Common reasons
- Eating little or no animal food, as in a vegan diet
- Long-term use of acid-lowering medicines for heartburn or ulcers
- Some diabetes medicines, taken for a long time
- Less stomach acid with age, which makes B12 harder to absorb
- Past stomach or weight-loss surgery
- Gut conditions such as celiac disease or Crohn's disease
- Less often: pernicious anemia, an immune condition that blocks B12 absorption
What can throw it off
Recent B12 supplements or shots raise the result, and high-dose biotin can throw off some B12 tests.
Questions to take to your appointment
- 1Should I have a follow-up test, like MMA?
- 2Could my medicines or diet explain this?
- 3Should my blood count and folate be checked too?
Read together with
Doctors rarely read Vitamin B12 alone. These usually sit next to it.
Quick answers
What is the vitamin B12 blood test?
Vitamin B12: A vitamin needed for healthy nerves and red blood cells. The body needs vitamin B12, found in animal foods and foods with added B12, for nerves and red blood cells. Absorbing it takes stomach acid and intrinsic factor, a protein made in the stomach. A result near the low end may be checked with a follow-up test, methylmalonic acid (MMA).
What is a normal vitamin B12 level?
For most adults, vitamin B12 is typically 200 to 800 pg/mL. Some countries print it in pmol/L, so check the unit first. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high vitamin B12 mean?
A high B12 is most often from supplements, B12 shots or foods with added B12. If none of these apply, doctors may look at the liver and the blood count. Common reasons include vitamin B12 supplements, multivitamins or energy drinks; B12 shots in the weeks before the test; and less often: liver disease or some blood and bone marrow disorders. A doctor reads it together with your other results and how you feel.
What does a low vitamin B12 mean?
A low B12 can come from diet, from trouble absorbing it, or from some medicines. When the result is close to the cutoff, a follow-up MMA test can help confirm it. Common reasons include eating little or no animal food, as in a vegan diet; long-term use of acid-lowering medicines for heartburn or ulcers; some diabetes medicines, taken for a long time; and less stomach acid with age, which makes B12 harder to absorb.
What can affect my vitamin B12 result?
Recent B12 supplements or shots raise the result, and high-dose biotin can throw off some B12 tests.
What should I ask my doctor about my vitamin B12?
Questions worth taking to the appointment: Should I have a follow-up test, like MMA? Could my medicines or diet explain this? Should my blood count and folate be checked too?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
Vita: Health Coach on the App StoreSources
- ABIM — Laboratory test reference ranges (January 2026)
- Merck Manual Professional — Vitamin B12 deficiency
- MedlinePlus — Vitamin B12 level
Stuck on a word? See the medical words. How we choose our sources. More about Vita Health Coach.