The Schilling test for pernicious anemia involves which of the following?

The Schilling test is specifically designed to evaluate the absorption of vitamin B12 in the body and diagnose pernicious anemia. In this test, radioactive cobalamin (a form of vitamin B12) is administered orally, and the subsequent excretion of this substance in the urine is measured over a specified period.

In a healthy individual, the body absorbs vitamin B12 from food in the intestine, and some of it will be excreted through the urine. However, in patients with pernicious anemia, which is caused by a lack of intrinsic factor leading to impaired absorption of vitamin B12, the amount of radioactive cobalamin excreted in urine will be significantly lower. Therefore, measuring the excretion of this radiolabeled vitamin provides critical insight into whether the issue is due to malabsorption of vitamin B12.

Using blood transfusion, performing dietary assessments, or conducting a bone marrow biopsy would not directly measure the absorption of vitamin B12 and would not provide the specific information needed to diagnose pernicious anemia or differentiate it from other types of anemia or malabsorption issues. Thus, the method involving the administration of radioactive cobalamin and measuring its excretion is the correct approach in determining the function of vitamin B12 absorption in