What diagnostic test is expected for a client suspected to have pernicious anemia?

The Schilling test is specifically designed to evaluate vitamin B12 absorption and is primarily used to diagnose pernicious anemia. Pernicious anemia occurs due to an inability to absorb vitamin B12 in the intestines, often resulting from a deficiency of intrinsic factor, a protein essential for B12 absorption. The Schilling test involves administering a dose of radioactive vitamin B12, followed by measuring the amount of vitamin B12 excreted in the urine over 24 hours. If the amount of B12 excreted is low, it indicates that the vitamin is not being absorbed effectively, which can suggest pernicious anemia.

Other diagnostic tests mentioned, like the sweat test, are used for diagnosing cystic fibrosis and do not relate to vitamin B12 absorption. Haptoglobin is a protein that binds free hemoglobin in the blood and is used to assess hemolytic anemia, while antinuclear antibodies are typically tested in autoimmune disorders. Hence, these tests would not provide the specific information needed for diagnosing pernicious anemia.