Serum Vitamin B12 (Cobalamin) 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 to ensure proper nutrient intake and prevent deficiencies that could affect your health."]
Key facts at a glance
- LOINC
- 103122-8
- Short code
- Silver Birch (rBet v) 6 IgE RAST
- Synonyms
- Silver Birch (rBet v) 6 IgE RAST
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- rast
- CPT
- 84484
- SNOMED
- 302774002
- 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 Is This Test Done?
Your healthcare provider may order this test if you have symptoms like fatigue, numbness or tingling in the hands and feet, weakness, or memory problems. It may also be done to diagnose or monitor conditions such as pernicious anemia, gastric bypass surgery, or malabsorption disorders.
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 your blood is drawn early in the morning. Bring any medications you’re taking, as some (like certain blood thinners) may affect results.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but it usually doesn’t cause significant discomfort. The blood sample will be sent to a lab for analysis.
What Are Possible Results?
Results are typically reported in picograms per milliliter (pg/mL) or picomoles per liter (pmol/L). Low levels may indicate deficiency, while high levels could suggest conditions like certain cancers or kidney disease.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low vitamin B12 levels are linked to anemia, neurological issues, and weakened immune function. Deficiency can develop from poor diet, malabsorption (e.g., due to celiac disease or atrophic gastritis), or conditions like Crohn’s disease. High levels may require further investigation to rule out underlying causes like liver disease or certain medications.
Short name
Vitamin B12 Level
Frequently asked questions
What causes vitamin B12 deficiency?
How long does it take to get results?
Can I take supplements to raise my vitamin B12 levels?
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