Schilling Test

Vitamin B12 Absorption Test

How It Is Done

  • You will be given a capsule to swallow. This capsule contains a very small amount of radioactive-tagged vitamin B12.
  • Two hours later, you will receive a shot of non-radioactive vitamin B12 in a muscle. This non-radioactive vitamin B12 prevents the radioactive B12 from binding to tissues in the body after it is absorbed.
  • You will then be asked to collect a 24-hour urine sample.
  • If the level of radioactive vitamin B12 is low, a second test may be done within 3 to 7 days. During the second test, you will be given a pill of intrinsic factor with the radioactive vitamin B12. You will then need to collect another 24-hour urine sample.
  • On rare occasions radioactive vitamin B12 will not be present in the urine, even after intrinsic factor is given along with the radioactive vitamin B12. This may be caused by bacteria in the intestine or a problem in the pancreas. If your health professional suspects bacteria are causing abnormal test results, a third test may be done after you take some antibiotics to destroy the bacteria. If your health professional suspects a problem with your pancreas, the Schilling test may be repeated after you take some pancreatic medications (pancreatic enzymes).

Urine collection over 24 hours

  • The collection period usually starts in the morning. When you first get up, empty your bladder but do not save this urine. Write down the time that you urinated to mark the beginning of your 24-hour collection period.
  • For the next 24 hours, collect all your urine. Your health professional or lab will usually provide you with a large container that holds about 4 L (1 gal) and has a small amount of preservative in it. Urinate into a smaller, clean container and then pour the urine into the large container. Avoid touching the inside of the container with your fingers.
  • Keep the large container in the refrigerator during the collection period.
  • Empty your bladder for the final collection at or just before the end of the 24-hour period. Add this final sample to the large container and record the time.
  • Avoid getting toilet paper, pubic hair, stool (feces), menstrual blood, or other foreign matter in the urine sample.

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Author: Jan Nissl, RN, BSLast Updated: April 13, 2007
Medical Review: Anne C. Poinier, MD - Internal Medicine
Kathleen Romito, MD - Family Medicine
Brian Leber, MDCM, FRCPC - Hematology

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Topic Contents
 Test Overview
 Why It Is Done
 How To Prepare
Arrow PointerHow It Is Done
 How It Feels
 Risks
 Results
 What Affects the Test
 What To Think About
 References
 Credits