Direct colorimetric monoclonal antibody enzyme immunoassay for estradiol-17β in saliva

We developed a direct microtiter plate enzyme immunoassay to measure estradiol-17β in saliva. The assay has a commercially available monoclonal antibody, raised against estradiol-17β-6-carboxymethyloxime-bovine serum albumin, and a homologous horseradish peroxidase conjugate measured colorimetrically. The detection limit (equivalent to B(o) -3 SD) is 365 amol/well or 7.3 pmol/L when 50-μL samples are assayed. Cross-reactivity with estrone and estriol, testosterone, or progesterone is <0.2%. Estradiol- 17β was measured in daily samples over five natural menstrual cycles and eight cycles stimulated as a preliminary to in vitro fertilization, and the concentrations and fluctuations found agreed with previously published data. This method gives results in ~3 h and may be useful for fertility monitoring and management.