Evaluation of five commercially available direct radio-immunoassays for the determination of 17 beta-estradiol in serum for the hormonal monitoring of ovarian stimulation.

Five direct radio-immunoassay kits for the dosage of 17 beta-estradiol were assessed for their usefulness to monitor the serum values of 17 beta-estradiol in stimulated and natural ovarian cycles. Prerequisites included a turn-around time of 4 hours for an assay of 100 tubes and a range extended to at least 2,000 ng/l. The following parameters were evaluated: characteristics of the standard curve, sensitivity, precision profile, within- and between-assay precision, analytical drift and linearity. We found that the five tested methods are technically suitable to monitor serum 17 beta-estradiol in stimulated cycles but they all lack precision for low 17 beta-estradiol levels as seen in the early follicular phase of natural cycles.