Clinical Chemistry, Vol 19, 1357-1360, Copyright © 1973 by the American Association for Clinical Chemistry

Comparison of Two Methods for Radioassay of Vitamin B₁₂ in Serum

¹ E. L. Overton Hematology-Oncology Research Laboratory, Departments of Internal Medicine and Biostatistics, University of Texas Southwestern Medical School at Dallas, and Nuclear Medicine Service, VA Hospital, Dallas, Tex, 75235.

A reference radioassay for vitamin B₁₂ in serum, in which human serum is used as binder and DEAE-cellulose is used to separate free and bound B₁₂, was compared (194 sera) with a packaged kit (" Phadebas B₁₂ Test"), in which intrinsic factor is used as binder and polysaccharide for separation. The correlation coefficient was 0.949. With the kit, added B₁₂ was identifiable, proportional dilution characteristics were excellent, and serial reproducibility was good. The normal range for the reference assay was 200-1000 pg/ml; all B₁₂-deficient patients had values of <165 pg/ml. In a separate study, 38 patients with documented (clinical and laboratory) B₁₂ deficiency had mean serum values of <150 pg/ml by the reference assay, 250 pg/ml by the kit. For the kit, the normal range was 250-1100 pg/ml. All patients with serum values of <150 pg/ml by kit assay were B₁₂ deficient; false positives were seen in the 150-250 pg/mI range.

Submitted on July 23, 1973

The following articles in journals at HighWire Press have cited this article:

				G. S. EISENBARTH, P. W. WILSON, F. WARD, C. BUCKLEY, and H. LEBOVITZ The Polyglandular Failure Syndrome: Disease Inheritance, HLA Type, and Immune Function: Studies in Patients and Families Ann Intern Med, October 1, 1979; 91(4): 528 - 533. [Abstract] [PDF]