Estradiol (C₁₈H₂₄O₂), also known as E2, is a major female sex hormone (strongest estrogen) which regulates menstrual reproductive cycles as well as the estrous cycle. It is a key regulator of growth, differentiation, and function in a wide array of tissues, including the male and female reproductive tracts, mammary gland, brain, skeletal and cardiovascular systems. E2 has two distinct intracellular receptors; ERα and ERβ which are mediating the main biological functions of E2. ERα and ERβ are encoded by unique genes possessing the functional domain characteristics of the steroid/thyroid hormone superfamily of nuclear receptors. ERα, as the predominant form, is expressed in the breast, uterus, cervix, and vagina., whereas ERβ exhibits a more limited pattern and is primarily expressed in the ovary, prostate, testis, spleen, lung, hypothalamus, and thymus.

The ZellX® Estradiol ELISA kit is a competitive ELISA kit designed to quantitatively measure Estradiol and its metabolites present in urine, extracted dried fecal samples, and tissue culture media. This kit is not recommended for serum, plasma, or saliva samples due to low concentration of Estradiol in such samples. For analyzing Estradiol in serum and plasma use our High sensitivity Estradiol ELISA Kit Cat. No. ZX-55108-96.