Evidence That Some Patients with Pernicious Anemia Are Not Recognized by Radiodilution Assay for Cobalamin in Serum

Abstract

FOR the past 25 years, serum levels of cobalamin (vitamin B₁₂) have been determined reliably by means of microbiologic assays. These procedures, however, are time consuming and have been available in only a limited number of institutions. The development of radiodilution assays for measuring the serum cobalamin level has met the need for a rapid and simple method and has made this determination generally available. Undoubtedly, the majority of serum cobalamin levels determined on patients at present use one of the radiodilution assays.Radiodilution assays involve extraction of bound cobalamin from a sample of serum, its conversion to . . .