The Schilling test may have been historically ordered for patients suspected of having which condition?

The Schilling test is specifically designed to assess vitamin B12 absorption in the body. It helps determine whether a patient has pernicious anemia, a condition characterized by the inability to absorb vitamin B12 due to a deficiency of intrinsic factor, a protein produced in the stomach. When intrinsic factor is lacking, even with adequate dietary intake, the body cannot absorb enough vitamin B12, leading to the development of anemia.

This test involves administering a dose of radioactive vitamin B12 and measuring how much is excreted in the urine. If a patient with suspected pernicious anemia does not excrete sufficient amounts, it indicates a problem with absorption, confirming the diagnosis. Thus, the Schilling test’s historical use is linked primarily with pernicious anemia, making that choice the correct answer in this context.