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Vitamin B12 (Serum or Plasma Concentration)

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

["A vitamin B12 test helps check if you have a deficiency that could affect your health."]

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

Key facts at a glance

LOINC
22290-1
Short code
EBV VCA IgA Titr Ser
Synonyms
EBV VCA IgA Titr Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 numbness or tingling in your hands and feet, weakness, fatigue, memory problems, or a sore tongue. It may also be done if you have conditions like pernicious anemia, gastrointestinal disorders, or if you follow a strict vegetarian or vegan diet, as these can increase the risk of vitamin B12 deficiency.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8 to 12 hours before the test if it involves drawing blood from your arm. If you are taking vitamin B12 supplements, your doctor may advise you to stop them for a few days before the test.

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 pain. The blood is then sent to a lab for testing.

What the Results Mean

Low levels of vitamin B12 can indicate deficiency, which may require treatment such as injections, oral supplements, or changes to your diet. High levels may not always have a clinical significance but could be checked for other conditions. Your doctor will discuss the results with you and decide if further tests or treatment is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin B12 deficiency can lead to serious health problems if left untreated. These include anemia, nerve damage, cognitive issues, and an increased risk of heart disease. Early detection and treatment can help prevent these complications and improve overall health.

Short name

Vitamin B12 Level

Frequently asked questions

What causes vitamin B12 deficiency?
Vitamin B12 deficiency can be caused by several factors, including poor diet (especially if you don’t eat enough meat, fish, or dairy), conditions that affect the absorption of vitamin B12 in the stomach (like pernicious anemia), long-term use of certain medications, or gastrointestinal disorders.
How is vitamin B12 deficiency treated?
Treatment for vitamin B12 deficiency usually involves supplements. If absorption is the issue, you may receive injections of vitamin B12. Oral supplements can also be prescribed, but they may not be as effective for severe deficiencies. Lifestyle changes, such as including more vitamin B12-rich foods in your diet, can help prevent future deficiencies.
Can vitamin B12 levels be affected by other health conditions?
Yes, certain health conditions and medications can influence vitamin B12 levels. For example, kidney disease, certain cancers, and long-term use of antacids or proton pump inhibitors can affect how well your body absorbs vitamin B12. Always discuss any concerns or symptoms with your doctor.
  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