Estriol is one of three estrogen hormones. Estriol levels rise throughout pregnancy, helping to keep your uterus and unborn baby healthy. The levels are at their highest right before childbirth. They help prepare your body for labor and delivery.
Everyone makes estriol. But in people who aren’t pregnant, the levels are almost undetectable. Other names for estriol include oestriol and E3.
During pregnancy, estriol:
- Helps your uterus grow as the fetus gets bigger.
- Makes your body more sensitive to other pregnancy hormones.
- Prepares your body for labor and delivery and breastfeeding.
The third estrogen is known as Estriol (E3) and is produced in significant amounts during pregnancy. In men and women, Estriol is irreversibly produced by estradiol (estriol cannot make estradiol) or from estrone through 16-OH-Estrone which makes it the largest circulating estrogen because both Estrone and Estradiol can make it. Despite this, estriol is not nearly as potent as estradiol (Estradiol is 80x more potent!). The least potent of the estrogens, Estriol (E3) levels are traditionally used clinically to gauge the viability of pregnancies. In the context of this profile, estriol is least likely to be associated with high-estrogen problems (e.g. breast cancer), and is generally viewed as a "protective" estrogen. Conversion of 16alpha-hydroxyestrone to estriol is important to consider.
Note: If one is taking a "Bi-Est" or "Tri-Est" preparation, an elevated estriol is not unusual.
Reference Ranges:
| Adult Male | ≤0.18 ng/mL | ||||||
| Adult Female (Non-pregnant) | ≤0.21 ng/mL | ||||||
| Pregnancy | |||||||
| First trimester | ≤2.50 ng/mL | ||||||
| Second trimester | ≤9.60 ng/mL | ||||||
| Third trimester | ≤14.60 ng/mL | ||||||
References:
https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/81711
Estriol, Serum
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