Schilling test

Alternative names:

vitamin B12 absorption test

How the test is performed:

An intramuscular injection of nonradioactive vitamin B12 is given to bind all available vitamin B12 receptor sites (that is, places on cells that combine with and hold B12). This will facilitate rapid excretion of the radioactive vitamin B12, if it is absorbed, because there are no places in the body for it to adhere. Urinary B12 levels are measured after the oral ingestion of a small amount of radioactive vitamin B12. Intrinsic factor is a gastric substance that binds with vitamin B12 and allows it to be absorbed. Either the 1-stage Schilling test (without intrinsic factor) or the 2-stage Schilling test (with intrinsic factor) may be used. A second test will be conducted about 1 week after the 1-stage if the 2-stage Schilling test is given. A 3rd Schilling test may be performed after a course of antibiotics, if overgrowth of intestinal bacteria is suspected as the cause of inadequate vitamin B12 absorption.

A 24-hour urine sample is needed.
The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.

• On day 1, urinate into the toilet upon arising in the morning.
• Collect all subsequent urine (in a special container) for the next 24-hours.
• On day 2, urinate into the container in the morning upon arising.
• Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.

Infant:
Thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all). The infant should be checked frequently and the bag changed after the infant has urinated into the bag. For active infants, this procedure may take a couple of attempts--lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into the container for transport to the laboratory.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

How to prepare for the test:

Fast (except for water) for 8 hours before starting the test, then eat normally for the next 24-hours.

The health care provider may advise you to discontinue drugs that can affect the test (see "Special Considerations").

If the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel:

The injection of vitamin B12 may sting.

Why the test is performed:

The Schilling test is performed to evaluate vitamin B12 absorption. Normally, ingested vitamin B12 combines with an intrinsic factor, which is produced by cells in the stomach, and is absorbed in the distal part of the ileum (middle part of the small intestines).