Analysis of the cause of systematic error in estradiol radioimmunoassay (RIA)

Objective: To improve the accuracy of estradiol RIA by analysing the cause of systematic errors. Methods: Retrieval assay, hemolysis and analogous substances interference assay and methods-comparing assay were used to analyse the systematic error. Results: Retrieval assay: retrieval rates were 101.6% and 104.3% when the adding concentration were 100.0 pg/ml and 360.0 pg/ml respectively. Haemolysis interference assay: the average interference value was -23.4%. The interference value of analogous substances interference assay were the followings: estriol 0.19%, estrone 13.1%, progesterone 0.11% and testosterone 0.45%. The result of methods-comparing assay (125I-RIA and 3H-RIA) was Y(125I-RIA)=16.84 + 1.11X(3H-RIA), t=11.75, p < 0.05. Conclusion: Haemolysis and estrone influence the RIA result to a greater extent. There is systematic error between the two detecting methods and serum estradiol 125I-RIA is more accurate