Serum or plasma concentration of vitamin B12 (substance concentration)
This test measures the amount of vitamin B12 in your blood. Vitamin B12 is essential for nerve function and red blood cell production.
["Vitamin B12 helps prevent nerve damage and anemia; low levels may indicate deficiencies or underlying health issues."]
Key facts at a glance
- LOINC
- 21594-7
- Short code
- VZV Ab Titr Ser
- Synonyms
- VZV Ab Titr Ser
- 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, weakness, numbness, or tingling in your hands and feet. It could also be part of a routine checkup for those at higher risk of deficiency, such as older adults, vegetarians, or individuals with certain gastrointestinal conditions.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves drawing blood from your arm. If you’re taking vitamin B12 supplements, let your provider know.
How the Test Is Performed
A healthcare professional will draw blood from a vein in your arm using a small needle. The blood sample is then sent to a lab for analysis.
What the Results Mean
Results are compared to a reference range, but exact values can vary by lab. Low levels may indicate vitamin B12 deficiency, which can be caused by poor diet, malabsorption, or certain medications. High levels might suggest recent vitamin B12 supplementation or other conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low vitamin B12 levels can lead to pernicious anemia, where the body cannot properly absorb vitamin B12, potentially causing nerve damage, cognitive issues, or weakness. High levels may require further investigation to rule out over-supplementation or other conditions affecting vitamin B12 metabolism.
Short name
Vitamin B12 Level
Frequently asked questions
What causes vitamin B12 deficiency?
How is vitamin B12 deficiency treated?
Can vitamin B12 levels be affected by other health conditions?
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