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Serum or Plasma Vitamin B12 (Cobalamin) with Rapid 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. Rapid confirmation helps ensure accurate diagnosis of deficiencies.

Quick summary

["Vitamin B12 levels help detect deficiencies that may cause fatigue, numbness, or neurological issues."]

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

Key facts at a glance

LOINC
91677-5
Short code
C parvum Ag Stl Ql IA.rapid
Synonyms
C parvum Ag Stl Ql IA.rapid
Category
coagulation
Sample
stool
Container
Clean container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia-rapid
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
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 unusual fatigue. It’s also used to monitor vitamin B12 levels in people with conditions like pernicious anemia, poor diet, or certain medications that interfere with absorption.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The test uses a rapid immunoassay method to detect and confirm vitamin B12 levels in your serum or plasma.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications, especially those affecting blood or vitamin absorption (e.g., proton pump inhibitors).

What Are Common Results?

Results are qualitative (qualitative test results indicate whether levels are low, normal, or high, but not exact numbers). Low levels may signal deficiency; further testing may be needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low vitamin B12 levels can lead to anemia, nerve damage, or cognitive issues. Early detection helps prevent long-term complications. Confirmation ensures accuracy, especially in cases where initial screening results are borderline or unclear.

Short name

Vitamin B12 (B12) Confirmation

Frequently asked questions

What causes vitamin B12 deficiency?
Deficiency can result from poor diet (e.g., vegan/vegetarian diets without fortified foods), malabsorption issues (e.g., pernicious anemia, Crohn’s disease), or certain medications.
What symptoms might I experience if my vitamin B12 levels are low?
Symptoms may include fatigue, weakness, numbness or tingling in hands/feet, memory problems, or balance issues. Some people have no symptoms until deficiency is severe.
How long does it take to get results?
Results are typically available within a few hours to a day, depending on lab processing times. Follow-up with your doctor if you have concerns about your results.
  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