Automated direct high-performance liquid chromatographic assay for estetrol, estriol, cortisone and cortisol in serum and amniotic fluid.

An automated direct assay for the simultaneous determination of unconjugated estetrol, estriol, cortisone and cortisol in serum and amniotic fluid, using high-performance liquid chromatography with electrochemical detection and ultraviolet detection, has been developed. The analysis time is ca. 1 h. This system offers good reproducibility with low coefficients of variation (estetrol, 2.3%; estriol, 2.3%; cortisone, 2.6%; cortisol, 1.9%). Detection limits are low enough for routine determinations (estetrol and estriol, 150 pg; cortisone and cortisol, 5 ng). Comparison of the values measured by the present method and by radioimmunoassay revealed significant correlations for estetrol (r = 0.787, p less than 0.01), estriol (r = 0.957, p less than 0.01), cortisone (r = 0.956, p less than 0.01) and cortisol (r = 0.865, p less than 0.01). This system proved to be valuable in monitoring feto-placental function.