Congenital Pernicious Anemia with Coexistent Transitory Intestinal Malabsorption of Vitamin B₁₂

Pernicious anemia with coexistent transitory intestinal malabsorption of vitamin B₁₂ has been established in adults. In this report a child with congenital pernicious anemia was documented to have had transitory selective intestinal malabsorption of vitamin B₁₂. The diagnosis of congenital pernicious anemia was established by the age of the patient, absence of intrinsic factor in gastric fluid, lack of antibodies to intrinsic factor and parietal cells, presence of HCl in gastric fluid, and normal gastric biopsy. The xylose excretion test, 72-hour fecal fat determination, upper gastrointestinal series, and biopsy of the jejunum were normal, but the Schilling test was abnormal with hog intrinsic factor of known potency on two occasions, indicating selective malabsorption of vitamin B₁₂. Seven months after therapy the Schilling test was still abnormal without intrinsic factor, but was normal with both human and hog intrinsic factor. The normal absorption with intrinsic factor after therapy is indicative that the selective malabsorption which was originally present was probably a consequence of the vitamin B₁₂ deficiency resulting from lack of intrinsic factor. In patients with abnormal radioactive vitamin B₁₂ absorption tests with administration of intrinsic factor, coexistent pernicious anemia must be excluded by demonstration of intrinsic factor in gastric fluid.