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Vitamin B12 (Serum) with Quantitative Measurement

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

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

Quick summary

["Low levels may indicate deficiencies or health conditions needing attention."]

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

Key facts at a glance

LOINC
14526-8
Short code
RUBV Ag Eye Ql IF
Synonyms
RUBV Ag Eye Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 doctor may order this test to check for vitamin B12 deficiency, which can cause symptoms like fatigue, numbness, or weakness. It’s also used to diagnose conditions such as pernicious anemia, certain gastrointestinal disorders, or malabsorption issues.

What Does the Result Mean?

Results may be below normal if you have a deficiency, but interpretation depends on your symptoms and medical history. High levels might suggest overconsumption or certain genetic conditions.

Common Reasons for Testing

Common reasons include unexplained fatigue, neurological symptoms, or if you have conditions like celiac disease, Crohn’s disease, or atrophic gastritis that may affect vitamin absorption.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the blood draw. Avoid supplements containing vitamin B12 for a few days if instructed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Vitamin B12 Deficiency Can Lead to Serious Health Issues

Short name

Vitamin B12 (Serum)

Frequently asked questions

How Long Does It Take to Get Results?
Results are typically available within 1–3 business days, depending on your lab’s processing time.
What If My Results Are Abnormal?
If your levels are low, your doctor may recommend dietary changes, supplements, or further testing (like folate or intrinsic factor tests) to determine the cause and treatment plan.
Does Diet Affect This Test?
While vitamin B12 is found in foods like meat, eggs, and dairy, your doctor may advise against dietary restrictions unless specified. Some supplements may interfere, so follow their guidance.
  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