The second-stage Schilling test (performed with intrinsic factor from hogs) is used to distinguish pernicious anemia from intestinal disorders such as Crohn's disease. We reviewed our experience with the second-stage test and found that inactive intrinsic factor caused the results to be misleading.
Eleven consecutive patients who were given a second-stage test are reported. The diagnosis of pernicious anemia was established in all 11 cases by demonstrating B12 deficiency and excluding other possible causes. Those who were recalled for additional absorption studies gave informed consent.
Vitamin B12 absorption was tested by measuring radioactivity in plasma (1) and in urine. After