Estradiol

Estradiol chemical structure Estradiol (8S,9S,13S,14S,17S)-13-methyl- 6,7,8,9,11,12,14,15,16,17-decahydro cyclopenta[un]phenanthrene-3,17-diol IUPAC name CAS number 50-28-2 ATC code G03CA03 PubChem 5757 DrugBank [2] Chemical formula {{{fórmula química}}} Peso molecular 272.39 Bioavailability 97-99% is bound Metabolism Liver Elimination half-life ~ 13 hours Excretion Urine Pregnancy category X (ESTADOS UNIDOS) Legal status S4 (Au), POM (REINO UNIDO), ℞-solamente (Estados Unidos) Routes of administration Oral, transdermal Estradiol (17β-estradiol) (also oestradiol) is a sex hormone. Labelled the "female" hormone but also present in males it represents the major estrogen in humans. Estradiol has not only a critical impact on reproductive and sexual functioning, but also affects other organs including bone structure. Contents 1 Síntesis 2 Production 3 Mechanism of action 4 Metabolismo 5 Measurement 6 Efectos 6.1 Female reproduction 6.2 Sexual development 6.3 Male reproduction 6.4 Bone 6.5 Liver 6.6 Cerebro 6.7 Blood vessels 6.8 Oncogene 6.9 Embarazo 7 Role in sexual differentiation 8 Estradiol medication 9 Terapia 9.1 Hormone replacement therapy 9.2 Blocking estrogens 9.3 Hormonal contraception 9.4 List of estradiol medications 10 Contraindicaciones 11 Efectos secundarios 12 Referencias 13 Ver también 14 External links Synthesis Conversion of testosterone to estradiol Estradiol, like other sex steroids, is derived from cholesterol. After side chain cleavage and utilizing the delta-5 pathway or the delta-4 pathway androstenedione is the key intermediary. Androstenedione is either converted to testosterone which in turn undergoes aromatization to estradiol, o, alternatively, androstenedione is aromatized to estrone which is converted to estradiol. Production During the reproductive years most estradiol in women is produced by the granulosa cells of the ovaries by aromatization of testosterone from the theca cells, or conversion of estrone to estradiol. Smaller amounts of estradiol are also produced by the adrenal cortex. In men, the testes produce estradiol. Estradiol is not only produced in the gonads. In both sexes precursor hormones, specifically testosterone, are converted by aromatization to estradiol. Particularly fat cells are active to convert precursors to estradiol, and will continue to do so even after the menopause. Estradiol is thus produced also in the brain and in the wall of arterial blood vessels. Mechanism of action Estradiol enters cells freely and interacts with a cytoplasmic target cell receptor. When the estrogen receptor has bound its ligand it can enter the nucleus of the target cell, and regulate gene transcription which leads to formation of messenger RNA. The mRNA interacts with ribosomes to produce specific proteins that express the effect of estradiol upon the target cell. Estradiol binds well to both estrogen receptors, ESα and ERβ, in contrast to certain other estrogens, notably medications that preferentially act on one of these receptors. These medications are called selective estrogen receptor modulators, or SERMs. Recently there has been speculation about a membrane estrogen receptor, ERX. Metabolism In plasma estradiol is largely bound to sex hormone binding globulin, also to albumin, -only a fraction is free and biologically active. Deactivation includes conversion to less active estrogens such as estrone and estriol. Estriol is the major urinary metabolite. Estradiol is conjugated in the liver by sulfate and glucuronide formation and as such excreted via the kidneys. Some of the watersoluble conjugates are excreted via the bile duct, and partly reabsorbed after hydrolysis from the intestinal tract. This enterohepatic circulation contributes to maintaining estradiol levels. Measurement Serum estradiol measurement in women reflect primarily the activity of the ovaries. As such they are useful the detect baseline estrogen in women with amenorrhea or menstrual dysfunction and to detect state of hypoestrogenicity and menopause. Furthermore estrogen monitoring during fertility therapy assesses follicular growth and useful to monitor the treatment. Estrogen-producing tumors will demonstrate persistent high levels of estradiol and other estrogens. In precocious puberty estradiol levels are inappropriately increased. Estradiol levels (blue line) during the menstrual cycle In the normal menstrual cycle estradiol levels measure typically