Vitamin B12 (Serum or Plasma Mass Concentration)
This test measures the amount of vitamin B12 (also called cobalamin) in your blood. Vitamin B12 is essential for nerve function, red blood cell production, and DNA synthesis.
["Check your vitamin B12 levels if you have symptoms like fatigue, numbness, or balance issues."]
Key facts at a glance
- LOINC
- 2132-9
- Short code
- Vit B12 SerPl-mCnc
- Synonyms
- Vit B12 SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 200
- Ref high
- 900
- 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 Is Done
Your doctor may order this test if you have symptoms that could be linked to low vitamin B12, such as weakness, tingling in the hands or feet, memory problems, or unusual fatigue. It’s also used to diagnose conditions like pernicious anemia, vitamin B12 deficiency, or malabsorption disorders.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw blood. The process takes about 5 minutes, and you may feel a slight pinch. If you’re on certain medications or have a bleeding disorder, let your doctor know beforehand.
What the Results Mean
Low levels may indicate vitamin B12 deficiency, which can affect how your body uses energy and produces red blood cells. High levels are less common but can sometimes be linked to genetic disorders or certain medications. Your doctor will discuss results in the context of your overall health.
Common Conditions Linked to Vitamin B12
Deficiency can cause anemia, nerve damage, or cognitive issues. Conditions like atrophic gastritis, celiac disease, or long-term vegan diets may lead to lower levels. Your doctor will evaluate symptoms and other test results to determine the cause.
Reference range
NCBI: Vitamin B12 200-900 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Vitamin B12 Level
Frequently asked questions
What causes vitamin B12 levels to drop?
How long does it take to get results?
Can vitamin B12 levels be affected by diet?
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 17, 2026. · Read our editorial policy