ESTRIOL — steroid hormone; an estra-1,3,5(10) - triene-3,16a, 17r - three - ol. AA. treats estrogen (see), however it biol. activity is low. In the conditions of a complete organism an orientation of action and final fiziol. effect E. decide by its ratio on other hormones.
In crystalline state E. G. F. Marrian from urine of pregnant women is for the first time received in 1930. Pier. the weight (weight) of hormone makes 288,39, g°pl280 °, [a]D + 61 ° (in chloroform).
In a human body and animals E. it is formed of estrone (see) and oestradiol (see) as a result of their 16a-hydroxylation; 60 — 80% of all excreted estrogen are the share of estriol. Excretion E. with urine at nonpregnant women in the period of an ovulation makes a day 18,2 ±2,2 mkg, in a phase of a yellow body of a menstrual cycle (see) — 17,0 ± 0,7 mkg; at men in days it is excreted on average 4,8 ± 0,6 mkg of estriol. At some morbid conditions (hepatopathies, dysfunctions of a thyroid gland, obesity, etc.) changes of concentration E are observed. in urine in comparison with norm that is a consequence of disturbance of metabolism of oestradiol and estrone.
At pregnancy products E. considerably increases (approximately by 1000 times while products of estrone and oestradiol increase only by 100 times). AA. during pregnancy it is synthesized
in a placenta (see), and it makes a body of the estrogen cosecreted by a placenta. In a placenta E. it is synthesized from 16а-гидроксиде-гидроэпиандростерон-сульфата, arriving from a fruit. In biosynthesis of this predecessor E. the adrenal glands of a fruit cosecreting degidroepiandrosteron-sul-veils and also a liver of a fruit where it is carried out it 16a-gidroksiliro-vaniye participate.
Dynamics of increase in excretion E. throughout pregnancy serves as a reliable indicator of viability of a fruit and normal functioning of a placenta. By the end of normally proceeding pregnancy excretion E. reaches 20 — 30 mg a day.
Bibliography: Reznikov A. G. Methods of definition of hormones, Kiev, 1980; Fizer JI. and Fizer M. Steroids, the lane with English, M., 1964; Physiology of endocrine system, under the editorship of V. G. Baranov, page 396, L., 1979; Longcope C. Est-riol production and metabolism in normal women, J. Steroid Biochem., v. 20, p. 959, 1984, bibliogr. V. S. Zelenetskaya.