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Vitamin B12 (Serum) 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

["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
32554-8
Short code
Vit B1 Bld-sCnc
Synonyms
Vit B1 Bld-sCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
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, memory problems, or a history of conditions that affect vitamin B12 absorption, such as pernicious anemia or celiac disease. It may also be part of routine screening for people at higher risk, like those with vegetarian or vegan diets, chronic gastritis, or certain gastrointestinal disorders.

What to Expect During the Test

A blood sample will be taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The test is quick and typically done in a doctor’s office or lab.

Preparation for the Test

No special preparation is needed for this test. However, if you’re taking certain medications that affect vitamin B12 levels, your doctor may advise you to stop them temporarily or discuss adjustments.

What the Results Mean

Results help determine if you have a vitamin B12 deficiency, which can lead to health problems if untreated. Your doctor will interpret the results in relation to your symptoms and medical history.

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 diet (e.g., strict vegetarian or vegan diets), conditions affecting absorption (like atrophic gastritis or celiac disease), or certain medications that interfere with absorption. It can also occur in people with conditions like pernicious anemia or those who’ve had stomach surgery.
How is vitamin B12 deficiency treated?
Treatment typically involves vitamin B12 supplements (oral, injections, or nasal sprays) to restore levels. Severe cases may require long-term supplementation. Lifestyle changes, such as ensuring adequate dietary intake (if applicable), can also help prevent recurrence.
Can vitamin B12 levels be affected by other health conditions?
Yes, conditions like kidney disease, certain cancers (e.g., stomach or pancreatic cancer), or autoimmune disorders can influence vitamin B12 levels. Chronic alcohol use and some medications (e.g., metformin, proton pump inhibitors) may also impact absorption or metabolism.
  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