Figure 4.

Schematic demonstrating TSH assay interference by heterophile antibodies (targeting assay reagents) and macro-TSH, which refers to the presence of circulating, bioinactive TSH held in complex by immunoglobulins. Although bioinactive, macro-TSH is immunoreactive and may be detected by laboratory immunoassays, resulting in spuriously high readings. Both types of antibody may affect fetal TSH results by transplacental passage. Created with BioRender.com.