Vitamin B12 (Serum or Plasma Concentration)
This test measures the amount of vitamin B12 in your blood, an essential nutrient for nerve function and red blood cell production.
["Vitamin B12 helps prevent anemia and supports brain health—low levels may signal deficiencies or underlying health concerns."]
Key facts at a glance
- LOINC
- 17528-1
- Short code
- Vit A 3h p SerPl-mCnc
- Synonyms
- Vit A 3h p SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters
Vitamin B12 is crucial for maintaining healthy nerve cells and preventing conditions like pernicious anemia. Low levels can cause fatigue, numbness, or cognitive issues. This test helps detect deficiencies early, especially in people with dietary restrictions (e.g., vegans/vegetarians) or conditions like celiac disease or stomach disorders.
What to Expect Before the Test
No special preparation is needed, but you may fast for 8–12 hours before the draw if instructed. Wear a loose shirt for easy access to your arm. The blood sample is taken from a vein in your arm, similar to other routine blood tests.
What the Results Mean
Results are compared to standard reference ranges for your age and health status. Very low levels may indicate vitamin B12 deficiency, while very high levels could signal conditions like kidney disease or certain medications. Your doctor will interpret results in the context of your symptoms and medical history.
Common Causes of Abnormal Results
Low vitamin B12 levels can stem from poor diet, malabsorption issues (e.g., atrophic gastritis), chronic illnesses, or medications like proton pump inhibitors. High levels may require further investigation to rule out conditions like liver disease or certain cancers.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Vitamin B12 deficiency is linked to neurological symptoms (e.g., tingling, memory loss) and megaloblastic anemia (large, immature red blood cells). Early detection allows for treatment with supplements or injections, preventing long-term damage. High levels may warrant follow-up to assess underlying causes, such as metabolic disorders or medication effects.
Short name
Vitamin B12 Level
Frequently asked questions
How long does it take to get my results?
What if my results are outside the normal range?
Can I take vitamin B12 supplements before the test?
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