Multicentric Standardization of a Bioassay for Thyroid Receptor Stimulating Antibodies

Abstract

In this doctoral thesis, the standardization process across several international laboratories for a bioassay detecting thyroid stimulating antibodies (TSAbs) is presented. This process consisted of using the 2nd IS for TSAbs to create a dose-response curve, where the linear range was identified. This linear range comprised 2nd IS concentrations between 5 mIU/L and 80 mIU/L. The linear range was then used to convert several previously selected patient serum samples from SRR% to mIU/L. The results of this process showed a high variability, especially when comparing the results of the two conducting laboratories, which was amplified by higher levels of TSAb respectively 2nd IS. A reason for the high variability could be identified in a differing behavior of the 2nd IS in comparison to the TSAb positive patient serum samples during measurement. This doctoral thesis shows the feasibility of standardizing a TSAb bioassay but at the same time demonstrates that the 2nd IS increases the variability of the bioassay’s results considerably. Conclusively, the 2nd IS might not be the best choice as a reference for the standardization process. This means that a different reference for standardization should be considered.