Estrona

For IN VITRO determination of serum or plasma ESTRONE
levels.
The origin of plasma estrogens in women has been precisely studied by refined
isotopic dilution techniques.
In normal women, most plasma estradiol is derived from the ovary, where theca cells
secrete androstenedione, which is then converted to estrone and then to estradiol by
the granulosa cells.
Little estrone is indeed formed and secreted by the ovary : most originates from a
peripheral conversion of estradiol and from the aromatisation of androstenedione, a
catalytic reaction essentially carried out in adipose tissue. In premenopausal
women, androstenedione is secreted by the ovary and the adrenals. In pregnant
women, the fetal adrenal gland provides a significant contribution to androstenedione
production. In menopausal women, estrone is the essential estrogen found in the
circulation, resulting from the conversion of adrenal androstenedione. An increase in
estrogen formation occurs with aging and in correlation with the amount of adipose
tissue. The estrogenic effects of estrone in menopausal women can produce
endometrial hyperplasia and bleeding but also maintains the bone mineral content.
In premenopausal women, excessive estrone blood levels can result from the
conversion of large amounts of androstenedione produced in micropolycystic ovary
syndrome and ovarian tumors. In such women, high estrone blood levels can
participate in a disturbance of the menstrual cycle.
Estrone in the circulation is essentially bound to albumin. This is important in the
interpretation of estrone-assay data. Indeed, and contrary to