intrinsic factor, a substance secreted by the gastric mucosa that is essential for the intestinal absorption of cyanocobalamin. Intrinsic factor forms a bond with molecules of cyanocobalamin, and this complex is transported across the ileal membrane. A deficiency of intrinsic factor, caused by gastrectomy, myxedema, or atrophy of the gastric mucosa, causes pernicious anemia. See also pernicious anemia.
