Results of serial measurement of estradiol in serum with six different methods during ovarian stimulation.

The aim of the study was to assess the values of serum estradiol (E2) in women undergoing ovarian stimulation with five direct commercial assays (IMX, Amerlite, Spectria, Vidas, CA) and to compare them with the results of an E2 direct method used in our laboratory. The study included 12 infertile women. Thirteen cycles were monitored daily during ovarian stimulation with transvaginal ultrasound and serum E2. Large differences were found between the E2 concentrations measured on the same sample with the different methods. In general the IMX and Amerlite assays gave the highest and CA the lowest results. The results of our own RIA and Spectria assay agreed more closely. The median ratio of the highest E2 value (IMX assay) and the lowest E2 value (CA value) was 1.75 (1.30-3.15). Values of E2 measured in serum depend on the method used. It is not possible to apply criteria from other studies directly to one's own patients. Close collaboration between the laboratories and the clinical staff is essential.