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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

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

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

Key facts at a glance

LOINC
44570-0
Short code
FLUBV Ab Ser Ql
Synonyms
FLUBV Ab Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Might Be Ordered

Your doctor may recommend this test if you have symptoms like fatigue, weakness, numbness, or tingling in your hands and feet. It could also be done if you have a history of poor diet, certain medical conditions, or medications that affect vitamin B12 absorption.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually causes only minor discomfort.

What the Test Results Mean

Low levels of vitamin B12 might indicate deficiencies caused by diet, malabsorption issues, or certain medical conditions. High levels may be due to genetic disorders or overproduction in the body.

Common Conditions Linked to Vitamin B12 Levels

Low vitamin B12 levels can lead to pernicious anemia, neurological problems, or other deficiencies. High levels might require further investigation to rule out rare conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin B12 plays a critical role in maintaining red blood cell health and nerve function. Abnormal results can signal underlying health concerns that need medical attention, such as deficiencies, malabsorption disorders, or genetic conditions.

Short name

Vitamin B12 Level

Frequently asked questions

What causes vitamin B12 levels to be low?
Low vitamin B12 levels can result from poor dietary intake (e.g., vegan diets), conditions affecting absorption (like pernicious anemia or Crohn’s disease), or certain medications that interfere with absorption.
What are the symptoms of low vitamin B12?
Symptoms may include fatigue, weakness, pale skin, numbness or tingling in hands/feet, balance problems, or memory issues. Some people may not show symptoms until deficiency is severe.
How often should I get this test?
Your doctor will determine frequency based on your health status, symptoms, and risk factors. Regular monitoring may be recommended if you have conditions like pernicious anemia or chronic kidney disease.
  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