Description of Schilling Test
The Schilling test is a vitamin B12 (cyanocobalamin) absorption test that indicates if a client lacks intrinsic factor by measuring excretion of orally administered, radiolabeled cyanocobalamin (vitamin B12) in a 24-hour urine sample. Vitamin B12 normally combines with intrinsic factor from the stomach and is absorbed in the terminal ileum. The test is based on the fact that, in normal clients, absorbed vitamin B12 in excess of the body's needs is excreted in the urine.
Because parenteral nonradiolabeled cyanocobalamin is also administered to saturate the vitamin B12 binding sites, all the radiolabeled cyanocobalamin should eventually be excreted in the urine. Because this test requires the use of radioactive cobalt and the diagnosis of pernicious anemia can be made using other tests, the Schilling test is no longer performed.
See Pernicious Anemia for a full listing of tests used to diagnose pernicious anemia.