Comparison between homogeneous phase radioassay and enzyme-linked immunosorbent assay for measurement of antithyroglobulin antibody content in serum. Relation to presence of thyroglobulin.

The aim of the study was to test the influence of thyroglobulin in vitro and in vivo on two different principles for quantification of serum antithyroglobulin antibody content. The methods employed were a previously described homogeneous phase radioassay and a newly developed enzyme-linked immunosorbent assay. Thyroglobulin inhibited the measurement of antithyroglobulin antibody content by both methods, not only by addition in vitro but also when present in vivo as a result of release from thyroid surgery. Both methods proved sufficiently sensitive as screening for presence of antithyroglobulin antibodies before measurement of thyroglobulin in serum. The study shows the importance of assessing the assay systems in each laboratory for interference before use, especially if intended for screening before quantifying serum thyroglobulin or for measurement of antithyroglobulin antibodies in other media (e.g. supernatants from lymphocyte cultures).