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 serious health issues like anemia or nerve damage."]
Key facts at a glance
- LOINC
- 17529-9
- Short code
- Vit A 6h p SerPl-mCnc
- Synonyms
- Vit A 6h 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 Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like fatigue, numbness, tingling in the hands or feet, weakness, or unexplained anemia. It’s also used to check for deficiencies in people with certain medical conditions (e.g., pernicious anemia, celiac disease, or those on long-term vitamin B12 supplements).
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your blood is collected early in the morning. Bring any medications or supplements you’re taking, as some (like certain B vitamins or iron supplements) can affect results.
What Happens During the Test
A healthcare professional will draw blood from a vein in your arm. The process is quick and usually painless. The blood sample is sent to a lab for analysis using a specialized method to measure vitamin B12 levels.
What the Results Mean
Results help determine if your vitamin B12 levels are too low, normal, or too high. Low levels may indicate a deficiency, while high levels could suggest certain medical conditions or medications. Your provider will discuss the results in the context of your overall health.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Vitamin B12 deficiency can lead to serious health problems over time, including anemia (reduced red blood cells), nerve damage, and cognitive issues. Early detection and treatment (often with vitamin B12 injections or supplements) can prevent complications. High levels may require further evaluation to rule out conditions like kidney disease or certain medications.
Short name
Vitamin B12 Level
Frequently asked questions
How long does it take to get my results?
Can I take vitamin B12 supplements before my test?
What if my results are low?
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