Estriol

Estriol (also oestriol) is one of the three main estrogens produced by the human body. It is only produced in significant amounts during pregnancy as it is made by the placenta. In pregnant women with multiple sclerosis (MS), estriol reduces the disease's symptoms noticeably, according to researchers at UCLA's Geffen Medical School.

Levels of estriol in non-pregnant women do not change much after menopause, and levels are not significantly different from levels in men.

Use in screening

Estriol levels can be measured to give an indication of the general health of the fetus. DHEA-S is produced by the adrenal cortex of the fetus. This is converted to estriol by the placenta.

If levels of "unconjugated estriol" are abnormally low in a pregnant woman, this may indicate a chrmosomal or congenital anomalies like Down's syndrome or Edward's syndrome. It is included as part of the triple test & quadrupole test for antenatal screening for fetal anomalies.

Because many pathological conditions in a pregnant woman can cause deviations in estriol levels, these screenings are often seen as less definitive of fetal-placental health than non-stress testing. Conditions which can create false-positives and false-negatives in estriol testing for fetal distress include preeclampsia, anemia and impaired kidney function.

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