A dedicated External Quality Assessment system for immunoassays of reproductive hormones

A dedicated External Quality Assessment (EQA) system for immunoassays of reproductive hormones (LH, FSH, prolactin, hCG, progesterone, estradiol, testosterone) and cortisol was developed. This catered for the needs of a group of laboratories conducting collaborative research with the WHO in the field of human reproduction. This system was designed to provide the maximum information on assay quality with the final aim of achieving and maintaining the highest possible comparability in monitored multi-center clinical studies. The EQA was based on the assays of 32 control samples per year in 4 quarterly assay runs and the evaluation of the following parameters: bias, between-run imprecision within a laboratory, number of outliers, frequency of returned assays of control samples, and between-laboratory imprecision. The data obtained were combined in a performance index for each laboratory, EQA run, and analyte. This index was then subjected to ranking. It may be assumed that the EQA system contributed to improvements of analytical work and/or the maintenance of a high assay quality in participating laboratories.