Enzyme-linked immunosorbent assay (ELISA) for IgG antibodies to thyroglobulin

We used a computer programmed standard IgG curve for computer-assisted quantification of assay results for autoantibodies to thyroglobulin (Tg) by quantitative enzyme-linked immunosorbent assay (ELISA). Specific antibody levels in unknowns were quantified by comparison of their optical density readings with a standard curve of absorbance vs concentration obtained with dilutions of the reference serum. Anti-Tg antibodies were detected in 80% of the patients with chronic thyroiditis and 90% of those with Graves' disease. Anti-Tg antibodies were also detected in 14.3% of the healthy controls. The titer of anti-Tg antibodies detected by tanned red cell hemagglutination correlated well with that detected by ELISA, although, the sensitivity of the ELISA was higher. By our computer-assisted conversion method, the anti-Tg antibody can be readily and reliably quantified and low titer antibodies to Tg can be detected with adequate precision.