Estrone (E1) | Laboratory research

General Information

Plasma estrone determination is recommended for: monitoring and diagnosing delayed puberty (mainly in girls), diagnosing sex hormone disorders, assessing the risk of fractures in postmenopausal women, diagnosing vaginal bleeding, determining the need for hormone replacement therapy, and monitoring antiestrogen therapy.

Estrone (E1) is a member of the estrogenic hormone family, which is involved in the development and maintenance of the female phenotype, the maturation of sex cells during pregnancy. They are also involved in the development of the nervous system, bone metabolism, and the proper functioning of the vascular endothelium. In the body of an adult woman (during non-pregnancy), estrogens are represented by: estrone (E1) and estradiol (E2). The third estrogen – estriol (E3) – is mainly represented during pregnancy. After menopause, E1 (estrone) is the main estrogen, and the levels of E2 and E3 decrease significantly.

Estradiol is mainly produced by the aromatization of testosterone in the ovaries and testes. A small amount is produced in the adrenal glands and peripheral adipose tissue.

In contrast, the majority of estrone is produced in the adrenal glands by aromatization of androstenedione. Estrone and estradiol can be converted to each other, and both can be inactivated by hydroxylation and conjugation. Circulating estradiol levels in the blood of nonmenopausal, nonpregnant women are 1,5–4 times higher than estrone.

Estradiol levels are much lower in men and postmenopausal women, while estrone levels vary little, leading to changes in the estradiol/estrone ratio at different times.

Estradiol levels in premenopausal women vary with the phases of the menstrual cycle. In the early follicular phase, its levels are low, begin to increase 2-3 days before ovulation, and increase rapidly during ovulation, reaching a maximum level before the peak of luteinizing hormone. This is followed by a slow decrease during ovulation. After this, estradiol levels increase again until the middle of the luteal phase, and then decrease to a minimum, then to the follicular phase.

Determination of estradiol is an essential part of the assessment of female reproductive function, infertility, oligo-amenorrhea and menopause. It is also used to monitor ovulation in preparation for in vitro fertilization.

When should we do the research?

Precocious or delayed puberty (predominantly in girls)

In disorders of the metabolism of sex hormones

To assess fracture risk in postmenopausal women

When monitoring hormone replacement therapy

When monitoring anti-estrogen therapy

Material for examination: Venous blood

Interpretation

Irregular cycles or absence of cycles with normal or high estradiol levels and increased estrone levels may indicate polycystic ovary syndrome, androgen-producing tumors, estrogen-producing tumors.

Gynecomastia, or other manifestations of feminization in men, is the result of an absolute or relative excess of estrogens in relation to androgens. The reasons for the increase of estrone and estradiol may be:

• An excess of androgens due to cancer or androgen therapy, accompanied by an excess of estrogens.
• Obesity - with hyperproduction of estrone
• Disruption of estrone and estradiol absorption processes - in liver diseases
• Estrogen-producing tumors
• Estrogen therapy with synthetic estrogen.