<prompt> A 58-year-old woman has a gastric ulcer, achlorhydria, and vibration sense loss in the lower extremities. She has a megaloblastic anemia. What test would help support a diagnosis of pernicious anemia?Response to injection of radioactive B12Endoscopic retrograde cholangiopancreatography ERCPProthrombin time PTRadiolabeled B12 given orally  <response>: The Schilling test is performed by giving radiolabeled B12 orally after saturating the B12 stores by intramuscular B12 . In pernicious anemia, less than 3 of the label is found in the 24-hour urine collection N7. Hemoglobin electrophoresis will detect defects in a- or b-globin chain synthesis, as seen in thalassemia Mediterranean anemia. 