Skip to content

Vitamin B12 (Serum) with Immunoassay Probe

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

This test measures your body’s level of vitamin B12, a vital nutrient needed for red blood cell production and nerve function.

Quick summary

["Low levels may indicate deficiencies or underlying health concerns requiring attention."]

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

Key facts at a glance

LOINC
81327-9
Short code
FLUBV Vic RNA Ct Resp Qn NAA+probe
Synonyms
FLUBV Vic RNA Ct Resp Qn NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 fatigue, weakness, or nerve problems. It’s also used to monitor conditions like pernicious anemia or malabsorption disorders.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a fasting protocol. Bring any medications you’re taking.

What Happens During the Test

A blood sample will be taken from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. The sample is sent to a lab for analysis using an immunoassay method to detect vitamin B12 levels.

What the Results Mean

Results help determine if your vitamin B12 levels are within normal ranges. Abnormal results may prompt further testing or treatment, such as dietary changes or vitamin supplements.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Vitamin B12 Deficiency

Short name

Vitamin B12 (Serum)

Frequently asked questions

Could my vitamin B12 levels be too low?
Yes, low levels may indicate deficiency, which can lead to anemia, nerve damage, or cognitive issues. Your doctor may recommend follow-up tests or treatments like B12 injections or supplements.
What causes vitamin B12 deficiency?
Common causes include poor diet (low intake), malabsorption (e.g., due to celiac disease or pernicious anemia), or conditions affecting vitamin absorption.
Do I need to take anything special if my results are abnormal?
If your results are low, your doctor may recommend dietary adjustments, supplements, or further testing. Follow their guidance closely to address the cause.
  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