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Schilling Test with Vitamin B12 Measurement (Urinary Excretion)

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

This test helps diagnose vitamin B12 deficiency by measuring how much vitamin B12 is excreted in your urine after ingesting a specific dose. It assesses how well your body absorbs vitamin B12, which is crucial for red blood cell production and nerve function.

Quick summary

["Check if your body absorbs vitamin B12 properly, often linked to pernicious anemia or other gastrointestinal issues."]

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

Key facts at a glance

LOINC
26820-1
Short code
S chartarum IgA-mCnc
Synonyms
S chartarum IgA-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 This Test Matters

Vitamin B12 deficiency can lead to serious health problems if untreated, including anemia, nerve damage, and cognitive issues. This test helps identify whether your absorption of vitamin B12 is impaired, which may require dietary changes, supplements, or medical treatment.

How the Test Works

You’ll take a pill containing radioactive vitamin B12 (or a non-radioactive version in some cases) and provide urine samples over several hours. The test measures how much vitamin B12 appears in your urine, indicating absorption efficiency.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications (especially those for stomach acid or acid reducers) that might affect absorption. Avoid high-vitamin B12 foods or supplements for a few days before testing.

Common Causes of Abnormal Results

Low urinary vitamin B12 excretion may suggest poor absorption due to conditions like pernicious anemia, celiac disease, or gastric bypass surgery. High levels could indicate overabsorption or a lab error, but this is rare.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin B12 Urine Test

Frequently asked questions

What does a low result mean?
A low result suggests vitamin B12 malabsorption, which may require further testing (e.g., gastric parietal cell antibodies) or treatment with B12 injections/oral supplements to prevent long-term nerve or blood cell damage.
What does a normal result mean?
A normal result indicates your body absorbs vitamin B12 well, but it doesn’t rule out mild deficiency. Follow-up blood tests (e.g., serum B12 or methylmalonic acid) may be needed if symptoms persist.
Can diet affect this test?
Yes—high-vitamin B12 foods (meat, eggs, dairy) or supplements can skew results. Avoid them for 24–48 hours before testing to get an accurate measure of natural 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