Skip to content

Serum or Plasma Vitamin B12 (Cobalamin) Concentration

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

This test measures the amount of vitamin B12, an essential nutrient needed for red blood cell production, nerve function, and DNA synthesis.

Quick summary

["Checks if your body has enough vitamin B12 for proper health."]

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

Key facts at a glance

LOINC
89040-0
Short code
RUBV Ab Ser Ql IF
Synonyms
RUBV Ab Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 deficiency can lead to anemia, nerve damage, or other serious health issues. This test helps identify low levels that may require dietary changes, supplements, or medical treatment.

What to Expect Before the Test

No special preparation is needed. You may eat and drink normally before your blood is drawn. The test involves a simple blood sample taken from a vein in your arm.

What the Results Mean

Results help doctors determine if you have a deficiency. Low levels may prompt further testing or treatment recommendations, while normal results suggest adequate vitamin B12 levels.

Common Causes of Low Vitamin B12

Deficiency can result from poor diet (especially in vegans/vegetarians), certain medications, or conditions like pernicious anemia or malabsorption disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin B12 Level

Frequently asked questions

What triggers might lead to needing this test?
Your doctor may order this test if you have symptoms like fatigue, weakness, numbness, memory problems, or if you have conditions like pernicious anemia, poor diet, or recent weight loss.
How often should I get this test?
Frequency depends on your health status. People with known deficiencies or risk factors may need testing more often, while others may only need it if symptoms arise or as part of routine check-ups.
Can I take supplements before the test?
Yes, but follow your doctor’s advice. Some supplements may affect results, so check with your healthcare provider before taking them.
  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