Estrone-3-glucuronide, C24H30O8 , (1,3,5(10)-estratrien-3-ol-17-one glucosiduronate, E1G) is the principle secreted form of circulating estradiol in mammals. Clinical studies have indicated the utility of measuring estrone-3-glucuronide (E1G) and pregnanediol-3aglucuronide (PDG) in samples of urine to monitor ovarian function in females. There is substantial evidence supports an association of endogenous reproductive hormone exposure with increased risk of reproductive cancers. Greater estrogen exposure, assessed via indirect indicators such as number of years spent having menstrual cycles or direct indicators such as hormone measures , is associated with increased risk for cancers of the breast and ovary. BioVision’s E1G ELISA kit is a competitive ELISA assay for the quantitative measurement of E1G in extracted serum and plasma, or in urine, extracted dried fecal samples, and tissue culture media samples. Standards or diluted samples are pipetted into a clear microtiter plate coated with an antibody to capture rabbit antibodies. An E1G-peroxidase conjugate is added to the standards and samples in the wells. The binding reaction is initiated by the addition of a polyclonal antibody to E1G to each well. After incubation the plate is washed and substrate is added. The substrate reacts with the bound E1G-peroxidase conjugate. After a short incubation, the reaction is read at 450 nm wavelength.