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Serum/Plasma Substance Concentration (Bromocresol Green) for Vitamin B12

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

["Vitamin B12 levels help assess nutritional status and potential deficiencies that could affect your health."]

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

Key facts at a glance

LOINC
23328-8
Short code
OPPV Ab Mlk Ql
Synonyms
OPPV Ab Mlk Ql
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 doctor may order this test if you have symptoms like numbness, fatigue, or unusual weakness, or if you have conditions like pernicious anemia, gastrointestinal disorders, or recent dietary changes that might affect vitamin B12 absorption.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for a few hours before the blood draw if your test involves serum. Bring a list of medications to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause pain. The blood sample is then sent to the lab for analysis using a bromocresol green method.

What Are the Results?

Results are reported as a concentration of vitamin B12 in the blood. Low levels may indicate a deficiency, while higher levels may suggest overconsumption or certain medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

B12 (BCG)

Frequently asked questions

What causes low vitamin B12 levels?
Low vitamin B12 levels can be caused by dietary deficiencies (e.g., vegetarian or vegan diets without fortified foods), malabsorption issues (like pernicious anemia or celiac disease), or conditions affecting the stomach or intestines.
What are the symptoms of vitamin B12 deficiency?
Symptoms may include fatigue, weakness, numbness or tingling in hands and feet, balance problems, memory loss, or mood changes. Some people may not have symptoms until the deficiency is severe.
Can vitamin B12 deficiency be treated?
Yes, vitamin B12 deficiency is treatable with supplements (oral or injections) or dietary changes. Regular monitoring may be needed to ensure levels stay within a healthy range.
  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