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Vitamin B12 (Cobalamin) Mass Concentration

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["Checking your vitamin B12 level helps identify deficiencies that could cause fatigue, numbness, or other symptoms."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
16695-9
Short code
Vit B12 Bld-mCnc
Synonyms
Vit B12 Bld-mCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
200
Ref high
900
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 Is Done

Your doctor may order this test if you have symptoms like weakness, tingling in the hands or feet, memory problems, or unusual fatigue. It’s also used to monitor people with conditions like pernicious anemia, celiac disease, or those on certain medications that may affect vitamin B12 absorption.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. The process usually takes a few minutes. If you’re nervous, let your doctor or nurse know.

What the Results Mean

Low levels may indicate a vitamin B12 deficiency, which can be caused by poor diet, certain medical conditions, or medications. High levels are less common but may require further investigation.

Common Causes of Low Vitamin B12

Conditions like pernicious anemia (an autoimmune disorder), malabsorption issues (e.g., celiac disease), or long-term vegan diets can lead to low vitamin B12. Certain medications (like proton pump inhibitors) may also reduce absorption.

Reference range

NCBI: Vitamin B12 200-900 pg/mLN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin B12 Level

Frequently asked questions

What symptoms might I experience if my vitamin B12 level is low?
Symptoms of low vitamin B12 can include fatigue, weakness, numbness or tingling in the hands and feet, balance problems, memory loss, or mood changes. Some people may not notice symptoms until the deficiency is severe.
How is vitamin B12 deficiency usually treated?
Treatment typically involves vitamin B12 supplements (oral or injections) to restore levels. Lifestyle changes, such as a balanced diet rich in vitamin B12 (found in animal products), may also help. Follow-up tests may be needed to monitor progress.
Can vitamin B12 levels be affected by other health conditions?
Yes, conditions like kidney disease, certain infections, or long-term alcohol use can influence vitamin B12 levels. Always discuss your full medical history with your doctor to understand potential impacts on your test results.
  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 17, 2026. · Read our editorial policy