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Plasma or serum vitamin B12 concentration

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

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

Quick summary

["Vitamin B12 helps prevent nerve damage and supports red blood cell formation; 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
47283-7
Short code
PMV BldCo
Synonyms
PMV BldCo
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
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 Is This Test Done?

Your doctor may order this test to check for vitamin B12 deficiency, which can cause fatigue, numbness, weakness, or other neurological symptoms. It may also be used to monitor conditions like pernicious anemia, malabsorption disorders, or certain medications that affect vitamin B12 absorption.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw if your test involves a fasting sample. Bring any medications or supplements you’re taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The process is quick and typically causes mild discomfort. The blood is then sent to a lab for analysis.

What Are Possible Results?

Results are reported as a concentration of vitamin B12 in the blood. Low levels may indicate deficiency, while high levels could suggest certain medical conditions or medications. Your doctor will interpret the results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin B12 (B12) Level

Frequently asked questions

What Are Common Causes of Low Vitamin B12 Levels?
Low vitamin B12 levels can result from dietary deficiencies (e.g., vegan diets), malabsorption issues (e.g., pernicious anemia, celiac disease), chronic conditions (e.g., Crohn’s disease), or certain medications that interfere with absorption.
What Are the Symptoms of Vitamin B12 Deficiency?
Symptoms may include fatigue, weakness, numbness or tingling in the hands and feet, balance problems, memory loss, or mood changes. Some people may not show symptoms until the deficiency is severe.
How Is Vitamin B12 Deficiency Treated?
Treatment typically involves vitamin B12 supplements (oral, injections, or nasal sprays) to restore levels. Lifestyle changes, such as a balanced diet or avoiding certain medications, may also help prevent recurrence.
  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