What is estradiol and why is it so clinically significant?

When it comes to the word estradiol, not many people really understand it. In fact, it is estrogen, the most active hormone in women's bodies. It is a sign of the activation of gonadal function and changes cyclically with the menstrual cycle in adult women.

1. Overview

Estradiol (E2) is the most important and most active hormone among estrogens. It is a sign of the activation of gonadal function and changes cyclically with the menstrual cycle in adult women. E2 mainly comes from developing follicles or corpus luteum, and is synthesized by theca cells and granulosa cells of the ovary under the dual effects of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). After inactivation in the liver, E2 is converted to estrone (E1) and estriol (E3). In men, E2 is mainly synthesized and secreted by interstitial cells of the testis. The main physiological effects of E2 are to promote the development of female reproductive organs and secondary sexual characteristics; regulate the functions of the hypothalamus and pituitary gland through positive and negative feedback; promote bone growth, accelerate bone fusion, and affect the body's lipoprotein, water and salt metabolism.

2. Clinical Significance

(1) E2 is an important hormone indicator for evaluating ovarian function. E2 is an important indicator for the onset of puberty and the diagnosis of precocious puberty. Both are due to the increased secretion of FSH and LH, which promotes the increase of ovarian E2 secretion. It shows cyclical changes during the menstrual cycle of adult women, gradually decreases during menopause, and the decline is more obvious after menopause. E2 levels are significantly reduced in patients with premature ovarian failure.

(2) Ovarian tumors can abnormally secrete hormones, leading to elevated E2 levels. Diseases such as pituitary tumors, teratomas, and testicular interstitial cell tumors can cause increased E2 secretion, leading to male breast development. In addition, cirrhosis, multiple pregnancy, and male systemic lupus erythematosus (SLE) can all lead to elevated serum E2 levels.

(3) Primary gonadal dysgenesis such as ovarian dysgenesis or absence of ovaries, secondary gonadal insufficiency caused by hypothalamic or pituitary lesions, congenital adrenal hyperplasia, hydatidiform mole, etc. can all result in reduced serum E2 levels.

Possible diseases with high results:

Polycystic ovary syndrome, congenital ovarian dysgenesis