[Value of total thyroxine determination by fluorescence polarization in examination for dysthyroidism]

Total T4 has been measured by fluorescence polarization (Abbott TDX). The intra-assay variation coefficient is three fold smaller than that obtained by radioimmunoassay (T4 RIA). The interassay variation coefficient of T4 TDX (7%) is better than that of T4 RIA (9%). There is a strong correlation between the two methods (r = 0,95). The mean value of T4 TDX is significantly lower than that of T4 RIA in 218 euthyroid patients without treatment as well as in 92 euthyroid patients under T4 treatment and in 14 hypothyroid patients. In 30 hyperthyroid patients the mean values were identical. The automatization and the short time of manipulation (0,5 hour) allow to obtain the result during the consultation.