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Vitamin B12 (Serum) with Immunoassay Confirmation

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

This test measures your levels of vitamin B12, a crucial nutrient needed for nerve function and red blood cell production.

Quick summary

["Low levels may indicate deficiencies linked to fatigue, numbness, or anemia."]

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

Key facts at a glance

LOINC
86570-9
Short code
FLUBV IgM Ser Ql IA
Synonyms
FLUBV IgM Ser Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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 weakness, tingling in hands/feet, or unexplained anemia. It’s also checked in patients with conditions like pernicious anemia, poor diet, or certain medications that interfere with absorption.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications (especially those for heartburn, acid reducers, or certain antibiotics) that could affect results.

How the Test Works

A blood sample is drawn from a vein, usually in your arm. The sample is tested for vitamin B12 levels using an immunoassay method to detect and confirm the presence of the vitamin.

What the Results Mean

Results help identify if your vitamin B12 levels are too low or too high. Low levels may require dietary changes, supplements, or medical treatment to address underlying causes like malabsorption.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Chronic low levels can lead to neurological issues (e.g., memory problems, balance difficulties) or blood disorders (e.g., megaloblastic anemia). Early detection allows for timely intervention to prevent long-term damage.

Short name

Vitamin B12 (Confirm)

Frequently asked questions

What causes vitamin B12 deficiency?
Common causes include poor diet (vegan/vegetarian diets), conditions affecting stomach acid (e.g., atrophic gastritis), or intestinal disorders (e.g., celiac disease). Medications like proton pump inhibitors can also reduce 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.
Can I eat or drink before the test?
You can eat and drink normally, but avoid alcohol 24 hours before testing as it may affect vitamin B12 absorption.
  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