An enzyme linked immunosorbent assay (ELISA) for measurement of human serum thyroglobulin. Evaluation of the influence of thyroglobulin auto-antibodies.

The aim of the study was to develop an enzyme linked immunosorbent assay (ELISA) for measuring thyroglobulin (Tg) in human serum and to evaluate the influence of serum thyroglobulin auto-antibodies (TgAb) on the ELISA. The sensitivity of the ELISA was 2.1 micrograms/l. Serum Tg levels in healthy controls were from less than 2.1 to 55.5 micrograms/l (n = 46) (95% reference range). With serum Tg concentrations between 19.6 to 90 micrograms/l the within-assay coefficient of variation (CV) was from 4.5 to 6.6% (n = 12) and the between-assay CV from 8.5 to 10.5% (n = 6). The recovery from 20 to 89 micrograms Tg/l serum was from 93 to 101%. There was significant correlation between serum Tg concentrations measured by the ELISA and a RIA method in healthy controls (r = 0.85, n = 46, p less than 0.001) and in patients with differentiated thyroid carcinoma (r = 0.97, n = 28, p less than 0.001). The TgAb interfered with the serum Tg determination both in the ELISA and in the RIA method. The assay is simple and easy to perform, and the equipment is inexpensive and useful for large-scale serum Tg measurements as an alternative to RIA.