Interferences in quantitative immunochemical methods

Abstract

In the immunoassays, an antibody used as a reagent, detects an analyte (antigen) of interest. Although the noncovalent bound between analyte and complementary antibody is speci%c, false-positive and false-negative interferences are possible. Some interferences are similar to those in chemical analyses and some are typical only for immunoassays. One should suspect interferences in following cases: upon receiving an unacceptable result, if there is non-linearity during dilution, if there is no agreement with other test results or clinical data, if di9erent immunoassays in determination of the same analyte provide signi%cantly di9erent results. This paper reviews some of the possible interferences: 1) cross-reactivity with endogenous and exogenous non antibody-structured substances; 2) cross-reactivity with endogenous and exogenous antibody-structure substances; 3) the hook e9ect; and 4) the matrix e9ect. By knowing and recognizing interferences in immunoassays, one can avoid possible undesired consequences: diagnostic errors, treatment and monitoring of its e?cacy, unnecessary additional laboratory testing, unnecessary therapy.