Schilling s test

Mrs HJ is to undergo a Schilling s test. Explain how this test works, how it is performed and what it is used for ... 

Schilling s test assesses the oral absorption of vitamin B12 and is used to diagnose pernicious anaemia. The patient is injected intramuscularly with non-labelled vitamin B12, to saturate body stores. An oral dose of vitamin B12 labelled with cobalt-58 is administered, followed by a second dose labelled with cobalt-57 bound to intrinsic factor. Prior saturation of body stores ensures any absorbed radiolabelled vitamin B12 is rapidly excreted in the urine. Urinary excretion of orally administered vitamin B12 is low in patients with pernicious anaemia due to poor absorption. Absorption is increased when it is administered with intrinsic factor. The ratio of cobalt-57 to cobalt-58 is thus raised in patients with pernicious anaemia. Intrinsic factor antibody testing is now generally used to diagnose pernicious anaemia, though the Schilling s test may occasionally be used. 

B. The drug depresses vitamin B,2 levels and can lead to abnormal Schilling s test results. 

Schilling, Examination of Artillery Ammunition Exposed to Test in Operation Crossroad , PATR 1712 (1949) 26) K.S. Warren 0. 

B21. Brugge, W. R., Goff, J. S., Allen, N. C., Podell, E. R., and Allen, R. H., Development of a dual label Schilling test for pancreatic exocrine function based on the differential absorption of cobalamin bound to intrinsic factor and R protein. Gastroenterology 78, 937-949 (1980). 

When testing for B 2 absorption by the gut, a test for hoitvTCIl and apo-TCII has an advantage over the S chilling test. The Schilling test uses pure vitamin Bx, as a component of the test protocol. Because of this, the Schilling test cannot detect defects in B]2 absorption due to the lack of stomach acid or the lack of activity of gastric enzymes. The TCII test is sensitive to the these problems, but also to the lack of intrinsic factor Herbert et al., 1990). 

Cobalt-60 One of the most widely used of all radioactive isotopes is cobalt-60. In medicine, it is used to find and treat diseases. For example, it is used in a test known as the Schilling test. This test is a method for determining whether a person s body is making and using vitamin Bj2 properly. Two other isotopes of cobalt, cobalt-57 and cobalt-58, are used for the same purpose. 

Vitamin Bt2, Radioactive. Radioactive cyano-cobalamin radiocyan ocobalami n. Prepn of Co labelled compound Chalet et al. Science 111, 601 <1950). Properties identical with unlabelled vitamin Bl2, except for the presence of radioactive cobelt. Evaluation of dual-isotope Schilling test for pernicious anemia L. S. Zuckier, L. R. Chervu, J Nucl. Med. 25, 1032 (1984). 

The first suggestion to test ethyleneimines for mutagenic activity came to us in a letter from Brown University, Providence, Rhode Island, U.S.A., where a Ph.D. student (now Dr. C. E. Schilling of Knoxville, Pennsylvania) had noticed the pharmacological similarities between... 

---