Intrinsic factor blocking antibody interference is not detected in five automated cobalamin immunoassays.
OBJECTIVE
To systematically assess five automated cobalamin assays for intrinsic factor binding antibody (IFBA)-induced interference using pooled serum.


METHODS
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).


RESULTS
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.


CONCLUSIONS
Our results suggest that, under optimal conditions, the five automated cobalamin assays assessed are not susceptible to IFBA-mediated interference.
University of Utah/ARUP Laboratories, 500 Chipeta Way, Mail Code 115, Salt Lake City, UT 84108; e-mail: joely.a.straseski@aruplab.com.
Stephen D
SD
Merrigan
David T
DT
Yang
Joely A
JA
Straseski
D000906:Antibodies / Q000276:immunology*; D001331:Automation / Q000379:methods; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007437:Intrinsic Factor / Q000097:blood*; D012016:Reference Values; D015203:Reproducibility of Results; D014805:Vitamin B 12 / Q000032:analysis* / Q000276:immunology
D000906:Antibodies; D007437:Intrinsic Factor; D014805:Vitamin B 12
Cobalamin; Immunoassay; Interference; Intrinsic factor; Vitamin B12