Skip to content

Vitamin B12 (Serum or Plasma, Quantitative)

Published: August 9, 2026Updated: August 16, 2026

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.

Quick summary

["Check your vitamin B12 levels if you have symptoms of deficiency or need monitoring for nutritional health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
9576-0
Short code
RUBV Ab CSF IA-aCnc
Synonyms
RUBV Ab CSF IA-aCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Matters

Vitamin B12 deficiency can lead to serious health issues, including anemia, nerve damage, and cognitive problems. Your doctor may recommend this test if you have symptoms like fatigue, weakness, tingling in the hands or feet, or memory issues.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm. If you’re on a vitamin B12 supplement or have recent vitamin B12 injections, your doctor may ask you to stop temporarily.

How the Test Works

Blood is drawn and sent to a lab, where it is analyzed using an immunoassay method to detect and quantify vitamin B12 levels.

What the Results Mean

Results help identify whether your vitamin B12 levels are low, normal, or high. Low levels may indicate deficiency, while high levels could suggest over-supplementation or certain medical conditions.

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 deficiency?
Vitamin B12 deficiency can result from poor dietary intake (e.g., vegan/vegetarian diets), malabsorption issues (such as pernicious anemia or Crohn’s disease), certain medications (like proton pump inhibitors), or conditions affecting the stomach or intestines.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
Can vitamin B12 levels be affected by diet?
Yes, dietary factors play a key role. Foods rich in vitamin B12 include animal products (meat, fish, eggs, dairy), fortified foods (plant-based milks, nutritional yeast), and supplements. If you follow a plant-based diet, you may need to take a vitamin B12 supplement or receive injections to maintain adequate levels.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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