Dual isotope Schilling test for measuring absorption of food-bound and free vitamin B12 simultaneously

Am J Clin Pathol. 1983 Oct;80(4):490-5. doi: 10.1093/ajcp/80.4.490.


A prototype food-bound vitamin B12 (food-B12) absorption test has been developed in which 57Co-B12 was incorporated in vitro into egg yolk (yolk-B12) and served to volunteers in 50-g cooked portions together with toast and coffee for breakfast. Six hours later, 1 mg nonlabeled B12 was given intramuscularly and 24-hour urine was collected for radioactivity measurement. In separate tests, the absorption of yolk-B12 and crystalline 57Co-B12 was equally poor in patients with pernicious anemia. However, in patients with simple gastric achlorhydria and those who had undergone gastric surgery, the assimilation of yolk-B12 was impaired greatly, whereas the absorption of crystalline radio-B12 was normal. Egg yolk labeled with 58Co-B12 was administered together with crystalline 57Co-B12 in a dual isotope test with results similar to those obtained when the tests were prepared separately. This yolk-58Co-B12 test with its ability to detect malabsorption of food-B12 may be considered as an addition to the first part of the Schilling test.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Absorption
  • Achlorhydria / complications
  • Anemia, Pernicious / complications
  • Cobalt Radioisotopes
  • Egg White
  • Egg Yolk
  • Female
  • Gastric Mucosa / metabolism*
  • Humans
  • Schilling Test / methods*
  • Stomach / surgery
  • Vitamin B 12 / administration & dosage*
  • Vitamin B 12 / urine
  • Vitamin B 12 Deficiency / complications
  • Vitamin B 12 Deficiency / diagnosis*
  • Vitamin B 12 Deficiency / urine


  • Cobalt Radioisotopes
  • Vitamin B 12