Serum or plasma concentration of vitamin B12 (cobalamin)
This test measures the amount of vitamin B12, an essential nutrient needed for healthy red blood cells, nerve function, and DNA synthesis. Low levels may indicate deficiencies or underlying health conditions.
["Vitamin B12 helps prevent serious health problems like anemia and nerve damage."]
Key facts at a glance
- LOINC
- 22973-2
- Short code
- CAEV-AB
- Synonyms
- CAEV Ab Mlk Ql IA
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof milk collection vial or serum separator tube (SST) for serum samples
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (ELISA)
- Specimen volume
- 1-2 mL of milk or serum
- Stability
- Milk: Refrigerated (2-8°C) for up to 7 days; frozen (-20°C or below) for up to 30 days. Serum: Refrigerated (2-8°C) for up to 7 days; frozen (-20°C) for long-term storage.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test if you have symptoms like fatigue, weakness, numbness, or tingling in your hands and feet. It may also be done to check for pernicious anemia, malabsorption issues, or other conditions affecting vitamin B12 absorption.
What to Expect Before the Test
No special preparation is needed. You may have a blood sample drawn from a vein in your arm. If you’re taking vitamin B12 supplements, your doctor may ask you to stop temporarily to get an accurate result.
What the Results Mean
Results are compared to a standard range, but exact values can vary by lab. Low levels may suggest a deficiency, while high levels could indicate certain medical conditions or lab errors. Your doctor will discuss findings with you.
Common Causes of Low or High Levels
Low vitamin B12 levels can result from dietary deficiency, malabsorption (e.g., pernicious anemia, celiac disease), or conditions affecting absorption in the gut. High levels may be due to lab errors, certain medications, or rare genetic disorders.
Reference range
Negative: Antibodies to Caprine Arthritis Encephalitis Virus (CAEV) not detected. Positive: Antibodies to CAEV detected, indicating exposure or infection with the virus.N/A
No special patient preparation required for milk sample collection. Ensure sample is collected from a representative milking. For serum, collect via standard venipuncture into appropriate collection tube.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Vitamin B12 deficiency can lead to anemia, nerve damage, cognitive issues, or weakness. Early detection helps prevent long-term complications. Your doctor may recommend follow-up tests or treatments like supplements or dietary changes if needed.
Short name
Vitamin B12 Level
Frequently asked questions
What causes vitamin B12 levels to be low?
How long does it take to get results?
Can I eat or drink 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