American Journal of Clinical Nutrition, Vol 16, 402-411, Copyright © 1965 by The American Society for Clinical Nutrition, Inc.

Experiences with the Schilling Test as a Diagnostic Tool

¹ From the Division of Nutrition and Metabolism, Tulane Medical School, New Orleans, Louisiana

Multiple Schilling tests were given to normal subjects, patients with pernicious anemia and patients with malabsorption syndromes in the course of studies of the etiology of macrocytic anemias. Modified technics were carried out in an attempt to improve reproducibility and usefulness in diagnosis. Administration of a flushing dose of nonradioactive vitamin B₁₂ on the day after the standard Schilling test was of assistance in avoiding any carry over of radioactivity in subsequent tests.

In a majority of patients with macrocytic anemia, consistent results were obtained when tests were repeated at various intervals of time. In about 25 per cent of patients with pernicious anemia, results of Schilling tests performed months or years after the original test indicated malabsorption of vitamin B₁₂ in the presence of hog intrinsic factor. These results may be due to the development of antibodies to intrinsic factor. In a few patients with pernicious anemia, multiple Schilling tests gave results that varied from normal to those characteristic of intrinsic factor deficit or to intestinal malabsorption of other etiology. The normal absorption, which was observed occasionally, could be due to variation in the amount of endogenous intrinsic factor formed by the gastric mucosa. Concomitant folic acid deficiency is a possible explanation of a temporary defect in intestinal absorption or the defect might be due to severe vitamin B₁₂ deficiency per se.