They are lowest during the early follicular phase. E2 levels in premenopausal women fluctuate during the menstrual cycle. E2 levels in men and postmenopausal women are much lower than in nonpregnant women, while E1 levels differ less, resulting in a reversal of the premenopausal E2:E1 ratio. E2 circulates at 1.5 to 4 times the concentration of E1 in premenopausal, nonpregnant women. E2 demonstrates 1.25 to 5 times the biological potency of E1. E2 and E1 can be converted into each other, and both can be inactivated via hydroxylation and conjugation. By contrast, most of the circulating E1 is derived from peripheral aromatization of androstenedione (mainly adrenal). Small amounts are produced in the adrenal glands and some peripheral tissues, most notably fat. A third bioactive estrogen, estriol (E3), is the main pregnancy estrogen, but plays no significant role in nonpregnant women or men.Į2 is produced primarily in ovaries and testes by aromatization of testosterone. The 2 major biologically active estrogens in nonpregnant humans are estrone (E1) and estradiol (E2). They also are important for many other, nongender-specific processes, including growth, nervous system maturation, bone metabolism/remodeling, and endothelial responsiveness. **E2 levels vary widely through the menstrual cycle.Į2: pg/mL x 3.676=pmol/L (molecular weight=272)Įstrogens are involved in development and maintenance of the female phenotype, germ cell maturation, and pregnancy. *The reference ranges for children are based on the published literature(1,2), cross-correlation of our assay with assays used to generate the literature data, and on our data for young adults. Tanner stage V (adult) should be reached by age 18. Progression through Tanner stages is variable. There is evidence that it may occur up to 1 year earlier in obese girls and in African American girls. #Puberty onset (transition from Tanner stage I to Tanner stage II) occurs for girls at a median age of 10.5 (± 2) years. ![]() For boys, there is no proven relationship between puberty onset and body weight or ethnic origin. #Puberty onset (transition from Tanner stage I to Tanner stage II) occurs for boys at a median age of 11.5 (± 2) years. Monitoring antiestrogen therapy (eg, aromatase inhibitor therapy)ġ-14 days: Estradiol levels in newborns are very elevated at birth but will fall to prepubertal levels within a few days. Monitoring low-dose female hormone replacement therapy in postmenopausal women As an adjunct to clinical assessment, imaging studies and bone mineral density measurement in the fracture risk assessment of postmenopausal women, and, to a lesser degree, older men As part of the diagnosis and workup of suspected disorders of sex steroid metabolism (eg, aromatase deficiency and 17 alpha-hydroxylase deficiency) As part of the diagnosis and workup of precocious and delayed puberty in females, and, to a lesser degree, males ![]() Diagnosis of estrogen-producing neoplasms in males and, to a lesser degree, females Evaluation of feminization, including gynecomastia, in males In conjunction with luteinizing hormone measurements, monitoring of estrogen replacement therapy in hypogonadal premenopausal women Assessing ovarian status, including follicle development, for assisted reproduction protocols (eg, in vitro fertilization) Evaluation of hypogonadism and oligo-amenorrhea in females 14, 2022.All applications that require moderately sensitive measurement of estradiol: Physical Activity Guidelines for Americans.Obesity in pregnancy: Complications and maternal management. American College of Obstetricians and Gynecologists. ![]() Centers for Disease Control and Prevention. Gabbe's Obstetrics: Normal and Problem Pregnancies.
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