Vitamin B12 (Serum or Plasma Concentration)
This test measures the amount of vitamin B12 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 health and prevent deficiencies."]
Key facts at a glance
- LOINC
- 85821-7
- Short code
- FLUBV Vic Ag Islt Ql HAI
- Synonyms
- FLUBV Vic Ag Islt Ql HAI
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 1.5
- Ref high
- 9
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- hai
- CPT
- 83002
- 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 like fatigue, numbness, tingling in the hands or feet, weakness, or memory problems. It could also be done to diagnose or monitor conditions like pernicious anemia, vitamin B12 deficiency, or other blood 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 a blood draw is required. Bring any medications you’re currently taking to your appointment.
How the Test Is Performed
A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.
What the Results Mean
Low levels of vitamin B12 may indicate deficiency, which can lead to health problems over time. High levels might suggest certain medical conditions or medications affecting absorption. Your doctor will interpret the results in the context of your symptoms and medical history.
Reference range
Follicular: 1.5-9.0 mIU/mLN/A
For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Vitamin B12 deficiency can cause serious health issues, including anemia, nerve damage, and cognitive problems. Early detection and treatment can prevent long-term complications. Your doctor may recommend follow-up tests or treatments like vitamin B12 supplements or injections if needed.
Short name
Vitamin B12 Level
Frequently asked questions
What causes low vitamin B12 levels?
How long does it take to get results?
Can I take vitamin B12 supplements 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