Studies on the 57Co vitamin B12 plasma level absorption test.

Results of the (57)Co vitamin B(12) plasma level absorption test are described in 163 patients. The use of intramuscular carbachol with the test and the presence or absence of current vitamin B(12) therapy did not affect the test results. Injection of 1,000 mug of unlabelled vitamin B(12) during the test augmented plasma levels in patients with normal absorption but tests without this injection gave satisfactory differentiation between the normal and malabsorption ranges. Results from patients having had a gastrectomy, ileal resection, or a past history of adult coeliac disease are also described. Amongst patients with presumed Addisonian pernicious anaemia, two with unresolved equivocal results and three with falsely normal results were found. The significance of these is discussed.