Estrone-3-glucuronide (E1G) (E1G)

Estrone-3-glucuronide (E1G) is a major water-soluble metabolite of estrone and estradiol, produced primarily in the liver through the action of UDP-glucuronosyltransferases (UGTs) [6, 11]. It serves as a critical component of the estrogen excretion pathway, allowing for the elimination of steroid hormones via the kidneys into the urine [6, 7]. In clinical practice, E1G is widely utilized as a non-invasive biomarker for monitoring ovarian function and follicular development [2, 4]. Its urinary levels rise significantly during the follicular phase of the menstrual cycle, peaking approximately 24 to 36 hours before ovulation, which makes it a key analyte in home-based fertility monitors and ovulation prediction kits [4, 12]. Beyond its role as a biomarker, E1G acts as a substrate for several membrane transporters, including organic anion transporting polypeptides (OATPs) and multidrug resistance-associated proteins (MRPs), which facilitate its hepatobiliary and renal clearance [15]. While not a direct therapeutic target, its levels can be influenced by drugs that inhibit UGT enzymes or compete for transporter-mediated excretion [14, 15]. For instance, certain calcium channel blockers and antifungals have been shown to inhibit the glucuronidation process that forms E1G [14]. Understanding E1G dynamics is essential for managing infertility and assessing hormonal health in conditions such as polycystic ovary syndrome (PCOS) and menopause [1, 2].

Other names

Estrone 3-beta-D-glucuronideE1-3GEstrone glucuronide17-Oxoestra-1,3,5(10)-trien-3-yl beta-D-glucopyranosiduronic acidE1G

Not applicable (endogenous metabolite and biomarker)