The nurse implements which of the following for the client who is starting a Schilling test?
A. Administering methylcellulose (Citrucel).
B. Starting a 24- to 48 hour urine specimen collection.
C. Maintaining NPO status.
D. Starting a 72 hour stool specimen collection.
Correct Answer: B. Starting a 24- to 48 hour urine specimen collection.
Urinary vitamin B12 levels are measured after the ingestion of radioactive vitamin B12. A 24-to 48- hour urine specimen is collected after administration of an oral dose of radioactively tagged vitamin B12 and an injection of non-radioactive vitamin B12. In a healthy state of absorption, excess vitamin B12 is excreted in the urine; in a malabsorption state or when the intrinsic factor is missing, vitamin B12 is excreted in the feces.
Option A: Citrucel is a bulk-forming agent. Laxatives interfere with the absorption of vitamin B12. The patient is given radiolabeled vitamin B12 orally, following an intramuscular (IM) dose of unlabeled vitamin B12 one hour later. The injection is given to ensure that none of the radioactive B12 binds to any vitamin B12 depleted tissues, for example, the liver. A 24-hour urine collection monitors the absorption and the excretion.
Option C: The client is NPO 8 to 12 hours before the test but is not NPO during the test. If the previous stage provides an abnormal result, stage 2 can be done to assess whether there is a deficiency of intrinsic factor. Stage 1 is repeated along with an oral dose of intrinsic factor. A 24-hour urine collection is carried out to assess the level of vitamin B12.
Option D: A stool collection is not part of the Schilling test. If stool contaminates the urine collection, the results will be altered. During Stage 1, a healthy person will be able to absorb the administered radioactive B12 in their terminal ileum. It will then be excreted in the urine. If there are any defects with the cubam receptor at the terminal ileum, the result will show a low level of labeled cobalamin in urine as it will remain in the intestines and is likely to be excreted in feces.
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