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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

["Check your vitamin B12 levels to ensure proper body function and prevent deficiencies."]

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

Key facts at a glance

LOINC
24292-5
Short code
FLUBV Ab sp2 Titr Ser
Synonyms
FLUBV Ab sp2 Titr Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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, numbness, tingling in the hands or feet, weakness, or memory problems. It’s also used to diagnose conditions like pernicious anemia, nerve damage, or malabsorption issues.

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 draw if instructed. Bring your questions or any medications you’re taking.

How the Test Works

A blood sample is taken from a vein in your arm. The sample is sent to a lab for analysis using an immunoassay or similar method to measure vitamin B12 concentration.

What the Results Mean

Results help determine if your vitamin B12 levels are low, normal, or high. Low levels may indicate deficiency, while high levels could signal other health concerns like kidney disease or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin B12

Frequently asked questions

What causes low vitamin B12 levels?
Low vitamin B12 levels can result from poor diet (e.g., vegan/vegetarian diets), conditions affecting absorption (like pernicious anemia or Crohn’s disease), or certain medications that interfere with absorption.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will discuss them with you during your follow-up visit.
Can I take vitamin B12 supplements to fix a deficiency?
Yes, supplements or injections may be recommended to raise levels, but your provider will guide you on dosage and monitoring. Avoid self-treating without medical advice.
  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