Description

Estriol (E3) is one of the three main estrogens produced by the human body, the others being estradiol and estrone. When it’s measured in the blood, it’s typically done so in its conjugated form, meaning it’s bound to other molecules like sulfate or glucuronide. However, there’s also a fraction of estriol that circulates in its unconjugated or free form, denoted as 4E3. This measurement can be useful in certain medical contexts, such as assessing the health of pregnancy or evaluating hormonal balance in women.