Alpha-fetoprotein (AFP), beta human chorionic gonadotropin (ßhCG).

Carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA 19-9), cancer antigen 125 (CA 125).

Troponin, creatine kinase-MB isoenzyme, B-type natriuretic peptide (BNP).Immunoassays potentially affected by heterophile antibodies Cardiac markers Where suspected, the presence of heterophile antibodies interfering with the accuracy of investigations can be addressed through analysis by an alternative analytical platform, non-linearity of results on serial dilution or the use of heterophile-blocking reagents or immunoglobulin-blocking reagents. False lowering of thyroglobulin levels may also occur. Heterophile antibodies may also cause false depression of serum cortisol levels, resulting in incorrect diagnosis of hypothalamic-pituitary-adrenal axis insufficiency and inappropriate and potentially harmful replacement with glucocorticoids. Heterophile antibodies may affect a wide array of laboratory tests, resulting in false elevation of tumour markers, endocrine tests, cardiac injury markers and drug levels ( Table 1). Heterophile antibodies can also bridge the two antibodies independently of antigen, resulting in an increase in labelled antibody concentration ( Figure 2).įigure 2. The antigen in the sample bridges the two antibodies so that the amount of labelled antibody that binds to the solid-phase is proportional to the antigen concentration in the sample ( Figure 1). These assays use at least two antibodies directed against different epitopes of an antigen: one bound to a solid-phase, the other in solution and tagged with a signal moiety. Two-site immunometric or sandwich assays are particularly susceptible to analytical error in the setting of heterophile antibodies.

2 Sources proposed for the induction of heterophile antibodies include exposure to mice and mouse products, immunisation, blood transfusion, autoimmune diseases, dialysis and maternal transfer. 1 In eight automated tumour marker immunoassays, the prevalence of heterophile antibodies was 0.2–3.7%. The prevalence of heterophile antibodies is 0.17–40% in the general population.

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