Intrinsic Factor Blocking Antibody Interference Is Not Detected in Five Automated Cobalamin Immunoassays

Abstract

To systematically assess five automated cobalamin assays for intrinsic factor binding antibody (IFBA)-induced interference using pooled serum. Six pools created from IFBA-negative and IFBA-positive serum representing low, normal, and high cobalamin concentrations were analyzed before and after polyethylene glycol (PEG) precipitation of immunoglobulins on five cobalamin assays: the Centaur XP (Siemens Healthcare Diagnostics, Tarrytown, NY), IMMULITE 2000 (Siemens Healthcare Diagnostics), ARCHITECT i2000SR (Abbott Diagnostics, Abbott Park, IL), UniCel Dxl 800 (Beckman Coulter, Chaska, MN), and Modular E170 (Roche Diagnostics, Indianapolis, IN). Cobalamin concentrations before and after PEG treatment were similar, almost all within a 30% total allowable error, with no difference in pattern between the IFBA-negative and IFBA-positive pools regardless of the cobalamin concentration. Our results suggest that, under optimal conditions, the five automated cobalamin assays assessed are not susceptible to IFBA-mediated interference.