The EGG 57-CO B-12 absorption test, in the evaluation of patients with low serum B-12

The Schilling Test (ST) is the standard test for diagnosing vitamin B-12 malabsorption (MA). However, patients with subtle gastric dysfunction may have normal ST, but impaired absorption of B-12 given with food. The authors have adapted an Egg B-12 Absorption Test (EBAT) in which 57-Co cyanocobalamin (57-Co B-12) is mixed with scrambled egg to evaluate this phenomenon in patients with low serum B-12, normal ST and possible subtle MA. Lyophilized egg yolk is reconstituted and mixed with 57-Co- B-12 of equal dose to that of ST. The authors studied 46 individuals: 13 controls, 5 patients with known pernicious anemia (PA), in addition to 28 patients with low serum B-12 levels and normal ST. ST/EBAT ratios were calculated. Twenty-eight test patients excreted 13.3% on ST and 3.5% on EBAT. Mean ST/EBAT ratio was 8.2 (1.4-35.9). Five had EBAT results in the PA range (<1%) and ST/EBAT ratios (14.4-35.9) that were significantly elevated. This group is also evaluated with pepsinogen I/II ratios, gastric analysis, deoxyuridine suppression tests, anti intrinsic factor, and antiparietal cell antibodies. The authors' results indicate that the EBAT can differentiate between PA and non PA patients, and that some patients with low serum B-12 levels and normal ST may, in fact, have subtle MA. The EBAT, combined with ST/EBAT ratio, may provide a means for identifying this group of patients