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Serum or plasma concentration of vitamin B12 (cobalamin)

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

This test measures the amount of vitamin B12 in your blood. Vitamin B12 is essential for red blood cell production, nerve function, and DNA synthesis.

Quick summary

["Check your vitamin B12 levels if you have symptoms of deficiency or need monitoring for conditions like pernicious anemia or nerve damage."]

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

Key facts at a glance

LOINC
40750-2
Short code
EBV VCA IgG Ser Ql IF
Synonyms
EBV VCA IgG Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 Is This Test Done?

Your healthcare provider may order this test to diagnose or monitor conditions such as vitamin B12 deficiency, pernicious anemia, or malabsorption issues. It can also help assess nerve damage or other neurological symptoms. Additionally, it may be used in patients with certain gastrointestinal disorders or those on long-term medications that interfere with vitamin B12 absorption.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for a few hours before the blood draw, but this depends on your healthcare provider’s instructions. Bring any medications you’re currently taking to your appointment.

What the Test Involves

A healthcare professional will draw blood from a vein in your arm. The process is quick and typically causes only minor discomfort. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results can help determine if your vitamin B12 levels are too low, normal, or too high. Low levels may indicate deficiency, while high levels could be due to certain medical conditions or medications. Your doctor will interpret the results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin B12 deficiency can lead to serious health issues, including anemia (reduced red blood cells), nerve damage, cognitive problems, and weakness. Early detection and treatment can prevent these complications. High levels of vitamin B12 are less common but may signal underlying conditions like liver disease or certain cancers.

Short name

Vitamin B12 Level

Frequently asked questions

What causes vitamin B12 deficiency?
Vitamin B12 deficiency can result from poor diet (e.g., vegan or vegetarian diets without fortified foods), conditions that affect absorption (like pernicious anemia or Crohn’s disease), or certain medications that interfere with absorption. Lifestyle factors, such as smoking or heavy alcohol use, may also contribute.
How is vitamin B12 deficiency treated?
Treatment typically involves vitamin B12 supplements, either through injections, oral pills, or nasal sprays. Lifestyle changes, such as eating vitamin B12-rich foods (e.g., meat, fish, eggs, or fortified foods), may also help. Follow-up tests are often needed to monitor levels and adjust treatment as needed.
Can vitamin B12 levels be affected by other conditions?
Yes, conditions like kidney disease, certain cancers, or autoimmune disorders can influence vitamin B12 levels. Chronic alcohol use, long-term use of certain medications (e.g., metformin), or pregnancy may also impact results. Always discuss your full medical history 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