Vitamin B12 (Serum or Plasma Concentration)
This test measures the amount of vitamin B12 (also called cobalamin) in your blood. Vitamin B12 is essential for nerve function, red blood cell production, and DNA synthesis.
["Vitamin B12 helps prevent serious health issues like anemia and nerve damage."]
Key facts at a glance
- LOINC
- 27149-4
- Short code
- Vit B1 Bld Ql
- Synonyms
- Vit B1 Bld Ql
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Might You Need This Test?
Your doctor may order a vitamin B12 test if you have symptoms like fatigue, weakness, numbness or tingling in your hands and feet, memory problems, or a loss of balance. It may also be checked if you have conditions like pernicious anemia, gastrointestinal disorders, or if you’re on certain medications that can interfere with vitamin B12 absorption.
What to Expect During the Test
A blood sample is taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause pain. The blood is then sent to a lab for analysis.
What the Results Mean
Low vitamin B12 levels may indicate deficiencies caused by poor diet, malabsorption issues, or certain medical conditions. High levels are less common but can sometimes be linked to certain genetic disorders or overconsumption of supplements.
Common Causes of Low Vitamin B12
Vitamin B12 deficiency can result from dietary insufficiency (e.g., vegan diets), conditions like atrophic gastritis or pernicious anemia, or medications that reduce stomach acid production. It can also occur in people with gastrointestinal disorders or those who’ve had part of their stomach or intestines removed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Vitamin B12 deficiency can lead to anemia, neurological symptoms such as numbness or weakness, and long-term damage to the nervous system if untreated. Early diagnosis and treatment can prevent these complications.
Short name
Vitamin B12 Level
Frequently asked questions
What causes vitamin B12 deficiency?
How is vitamin B12 deficiency treated?
Can vitamin B12 levels be too high?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy