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Vitamin B12 (Serum) with Probe-Based Measurement

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

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

Quick summary

["Check your vitamin B12 levels to ensure proper health and prevent deficiencies."]

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

Key facts at a glance

LOINC
81325-3
Short code
FLUBV Yam RNA Ct Resp Qn NAA+probe
Synonyms
FLUBV Yam 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 This Test Matters

Vitamin B12 is essential for maintaining healthy nerve cells and preventing anemia. Low levels can cause fatigue, numbness, or neurological issues. This test helps identify deficiencies early.

How the Test Works

A small blood sample is taken to measure vitamin B12 concentration. The test uses a specialized probe to detect the vitamin’s presence in your serum.

Common Reasons for Testing

Doctors may order this test if you have symptoms like weakness, tingling in hands/feet, or unexplained anemia. It’s also part of routine checks for people at higher risk (e.g., vegetarians, older adults).

What to Expect Before the Test

No special preparation is needed, but inform your doctor about medications (e.g., certain blood pressure drugs) or recent vitamin supplements that might affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin B12 Level

Frequently asked questions

What does a low vitamin B12 level mean?
Low levels may indicate a deficiency caused by poor diet, malabsorption issues (e.g., pernicious anemia), or certain medical conditions. High levels are less common but could signal over-supplementation or rare genetic disorders.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab. Follow-up may be needed if results are outside expected ranges.
Can I take vitamin B12 supplements before testing?
Yes, but inform your doctor beforehand. Supplements may temporarily raise or lower results, so timing matters if you’re being monitored for changes.
  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