A Simultaneous Enzyme-Linked Immunoassay for Human Thyroglobulin

A “simultaneous” enzyme-linked immunoassay for the measurement of thyroglobulin in human serum was established using polyclonal rabbit antibody, in which rabbit anti-human thyroglobulin IgG-coated silicone rubber rod, rabbit anti-human thyroglobulin monovalent fragment (Fab')-β-D-galactosidase conjugate and serum sample were mixed at the same time. In order to improve the assay performance, an appropriate amount of Fab' -β-D-galactosidase conjugate was carefully chosen. The present assay was simple, rapid, highly sensitive and excellently reproducible. The sensitivity of the assay was approximately 1.5 amol/tube corresponding to 0.5 ng/ml using 2 μ1 of serum, which was higher than that in the two-step sandwich enzyme-linked immunoassay previously reported. The coefficients of variation for different levels of serum thyroglobulin determined by the present assay ranged from 3.4-7.2 % and 2.5-6.1 % for within and between run, respectively.