Serum or Plasma Vitamin B12 (Cobalamin) Concentration
This test measures the amount of vitamin B12, an essential nutrient needed for red blood cell production and nerve function, in your blood.
["Vitamin B12 helps prevent anemia and supports nerve health; low levels may indicate deficiency or underlying health issues."]
Key facts at a glance
- LOINC
- 5333-0
- Short code
- RUBV Ab Titr Ser LA
- Synonyms
- RUBV Ab Titr Ser LA
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- la
- 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 May 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, especially if you have conditions like pernicious anemia, gastrointestinal disorders, or are at higher risk for deficiency (e.g., strict vegetarians, older adults).
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the blood draw if your test uses a different method. Bring any medications you’re taking, as some (like certain blood thinners) may affect results.
How the Test Works
A small sample of your blood is taken from a vein in your arm. The lab then analyzes the sample to measure vitamin B12 levels using an immunoassay or similar method to detect its presence.
What the Results Mean
Results are compared to standard ranges, but exact values may vary by lab. Low levels may indicate vitamin B12 deficiency, while high levels could suggest certain medical conditions or lab errors. Your provider will discuss results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low vitamin B12 levels can lead to anemia (reduced red blood cells), nerve damage, or cognitive issues. It’s often linked to poor diet, malabsorption (e.g., from celiac disease or atrophic gastritis), or conditions like pernicious anemia. High levels may require further investigation to rule out lab artifacts or rare metabolic disorders.
Short name
Vitamin B12 Level
Frequently asked questions
What causes vitamin B12 deficiency?
Can vitamin B12 levels be affected by medications?
How long does it take to get results?
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