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Vitamin B12 (Cobalamin) with Serum or Plasma

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

This test measures your body’s level of vitamin B12, an essential nutrient needed for healthy red blood cells, nerve function, and DNA synthesis.

Quick summary

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

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

Key facts at a glance

LOINC
86318-3
Short code
FLUBV Yam Ag Islt Ql HAI
Synonyms
FLUBV Yam Ag Islt Ql HAI
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
1.5
Ref high
9
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
hai
CPT
83002
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, numbness, or balance issues. It’s also used to monitor conditions like pernicious anemia, malabsorption disorders, or certain medications that may deplete B12.

What to Expect Before the Test

No special preparation is needed unless instructed. You may have a blood sample drawn from a vein in your arm. If you’re on certain medications (like certain acid reducers), ask your doctor first.

What Happens During the Test?

A healthcare provider will clean the area, insert a small needle, and draw blood into a tube. The process usually takes a few minutes. You may feel a brief pinch, but it’s often over quickly.

What Are Possible Results?

Results are compared to standard ranges for your age and health. Low levels may signal deficiency, while very high levels could indicate conditions like certain cancers or kidney disease.

Reference range

Follicular: 1.5-9.0 mIU/mLN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin B12 deficiency is linked to neurological issues, anemia, and long-term damage if untreated. Early detection helps prevent complications like nerve damage or cognitive decline. Your doctor will discuss results and next steps based on your symptoms and lab findings.

Short name

Vitamin B12

Frequently asked questions

What causes vitamin B12 deficiency?
Deficiency can result from poor diet (e.g., vegan/vegetarian diets without fortified foods), malabsorption (e.g., pernicious anemia, Crohn’s disease), or certain medications interfering with 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. Your doctor will contact you with the final report.
Can I eat or drink before the test?
You can eat and drink normally unless your doctor specifies otherwise. Avoid alcohol 24 hours before testing, as it may affect 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