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Serum or Plasma Mass Concentration of Vitamin B12 (Cobalamin)

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

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

Quick summary

["Vitamin B12 helps prevent anemia and supports nerve health; 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
31507-7
Short code
MuV V Ab Ser-aCnc
Synonyms
MuV V Ab Ser-aCnc
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 This Test Might Be Ordered

Your healthcare provider may recommend this 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 alcohol use, or if you’re planning a pregnancy.

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 if your test is part of a metabolic panel. Bring any medications you’re currently taking to your appointment.

During the Test

A healthcare professional will insert a needle into a vein in your arm to draw blood. The process is quick and typically causes only a brief pinch. You may feel lightheaded for a moment afterward, but this usually passes quickly.

What the Results Mean

Results are compared to standard reference ranges for your age and health status. Low levels may signal vitamin B12 deficiency, while high levels may require further investigation to rule out other conditions like certain cancers or liver disease.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin B12 Level

Frequently asked questions

What are the normal reference ranges for this test?
Normal reference ranges can vary slightly by lab and demographic factors (e.g., age, pregnancy). Your healthcare provider will interpret your results in the context of your overall health and symptoms. Low vitamin B12 levels can lead to anemia, nerve damage, or cognitive issues, while very high levels may indicate conditions like vitamin B12 toxicity or certain metabolic disorders.
How often should I get this test?
Your provider will determine how often you need testing based on your health status, symptoms, or risk factors. For example, people with at-risk conditions (like autoimmune disorders or malabsorption issues) may need more frequent monitoring. Follow-up testing is often recommended if initial results are outside the expected range.
Can I take supplements to raise my vitamin B12 levels?
Yes, vitamin B12 supplements or fortified foods can help raise levels, but they won’t replace medical treatment if deficiency is due to an underlying condition (like pernicious anemia). Always consult your healthcare provider before starting supplements, especially if you’re on medications or have other health concerns.
  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