Skip to content

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 nerve function, red blood cell production, and DNA synthesis.

Quick summary

["Vitamin B12 helps prevent serious health issues like anemia and nerve damage."]

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

Key facts at a glance

LOINC
47314-0
Short code
FLUBV IgG Ser IA-aCnc
Synonyms
FLUBV IgG Ser IA-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 doctor may order this test if you have symptoms like fatigue, weakness, numbness, or tingling in your hands and feet. It may also be used to diagnose or monitor conditions such as pernicious anemia, malnutrition, or certain gastrointestinal disorders that affect 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 test if it involves drawing blood from your vein. If you have a urine sample, follow any specific instructions your healthcare provider gives you.

How the Test Is Performed

Blood is drawn from a vein in your arm, typically using a needle. The sample is then sent to a lab for analysis. If a urine sample is involved, you’ll collect a sample in a sterile container.

Possible Results and Their Meaning

Results can vary based on your health, diet, and other factors. Low levels may indicate vitamin B12 deficiency, while high levels might suggest certain liver diseases or overabsorption. 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.

◆Associated findings1

Short name

Vitamin B12 Level

Frequently asked questions

What causes vitamin B12 levels to be low?
Low vitamin B12 levels can result from poor diet (e.g., vegetarian or vegan diets without fortified foods), conditions affecting absorption (like pernicious anemia or celiac disease), or certain medications that interfere with absorption.
What are the symptoms of vitamin B12 deficiency?
Symptoms may include fatigue, weakness, numbness or tingling in the hands and feet, balance problems, memory loss, and mood changes. Some people may not have symptoms until the deficiency is severe.
How is vitamin B12 deficiency treated?
Treatment typically involves vitamin B12 supplements (oral, injections, or nasal sprays) to restore levels. Lifestyle changes, such as dietary adjustments or avoiding certain medications, may also be recommended.
  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