Endocrine Abstracts

Objectives: Free thyroxine (fT4) measurements are performed to detect thyroid disorders and monitor treatment. FT4 is measured using automated immunoassays (IAs) which face established analytical challenges due to low serum concentrations in the picomolar range and the precarious equilibrium between free and bound T4 (to thyroid-binding globulin (TBG) and (pre-)albumin). Furthermore, IAs are known to be affected by the composition of the serum sample (matrix-effects), which ca...