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Vitamin B12 (Serum or Plasma Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of vitamin B12, an essential nutrient needed for healthy nerve function and red blood cell production.

Quick summary

["Vitamin B12 helps prevent nerve damage and anemia; low levels may indicate deficiencies or underlying health conditions."]

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

Key facts at a glance

LOINC
17552-1
Short code
RUBV IgM CSF Ql
Synonyms
RUBV IgM CSF Ql
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order a vitamin B12 test if you have symptoms like fatigue, weakness, numbness, or tingling in your hands and feet. It may also be checked during routine blood work, especially if you have conditions like pernicious anemia, celiac disease, or chronic gastritis.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm to draw blood. If you’re concerned about needles, let your healthcare provider know.

What the Test Results Mean

Results are compared to a standard range. Very low levels may suggest vitamin B12 deficiency, while very high levels could indicate certain liver or kidney conditions. Your doctor will interpret results in the context of your health history.

Common Causes of Low or High Levels

Low vitamin B12 can result from poor diet, malabsorption issues, or conditions like pernicious anemia. High levels may be linked to liver disease, certain medications, or genetic factors.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin B12

Frequently asked questions

What Are My Next Steps If My Results Are Abnormal?
If your vitamin B12 level is low, your doctor may recommend dietary changes, supplements, or further testing to check for underlying causes like vitamin B12 deficiency anemia or other gastrointestinal disorders. Follow-up may include monitoring symptoms or additional blood tests.
Will I Need to Take Any Supplements?
If your doctor confirms a deficiency, they may prescribe vitamin B12 supplements (oral, injections, or nasal sprays) to restore levels. Always take supplements exactly as directed.
Can I Eat Foods High in Vitamin B12?
Yes! Foods like meat, fish, eggs, and dairy products contain vitamin B12. If you follow a vegetarian or vegan diet, you may need to take supplements or fortified foods to meet your needs.
  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