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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, an essential nutrient needed for red blood cell production and nerve function, in your blood.

Quick summary

["Vitamin B12 helps prevent anemia and supports nerve health; low levels may indicate deficiency or underlying health issues."]

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

Key facts at a glance

LOINC
7886-5
Short code
EBV VCA IgM Ser-aCnc
Synonyms
EBV VCA IgM Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 if you have symptoms like fatigue, weakness, numbness, or tingling in your hands and feet. It may also be used to diagnose pernicious anemia, vitamin B12 deficiency, or conditions affecting absorption in the gut.

What to Expect Before the Test

No special preparation is needed. You may have blood drawn from a vein in your arm. If you’re taking certain medications or have recent medical conditions, let your provider know.

What the Results Mean

Results are compared to standard reference ranges for healthy individuals. Low levels may signal deficiency, while very high levels could indicate conditions like certain cancers or kidney disease.

Common Causes of Abnormal Results

Low vitamin B12 levels can result from poor diet, malabsorption issues (e.g., pernicious anemia, celiac disease), or conditions affecting absorption in the stomach or intestines.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin B12 Level

Frequently asked questions

What symptoms might indicate a vitamin B12 deficiency?
Symptoms may include fatigue, weakness, pale or yellowish skin, numbness or tingling in hands/feet, balance problems, or memory loss. However, deficiencies can develop silently without obvious symptoms.
How is vitamin B12 deficiency typically treated?
Treatment usually involves oral supplements, injections, or dietary changes. Your provider may recommend follow-up tests to monitor levels and adjust treatment as needed.
Can vitamin B12 levels be affected by medications?
Yes, certain medications (e.g., proton pump inhibitors for acid reflux, metformin for diabetes) may interfere with vitamin B12 absorption. Always inform your provider about all medications you’re taking.
  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