What is Estriol Unconjugated / E3?

The secretion of estriol occurs through syncytiotrophoblast through fetal precursors. The majority of the hormone is conjugated which is frequented in maternal circulation while a small portion (around 10%)of it is unconjugated (uE3). The levels of unconjugated estriol are used to determine congenital abnormalities as well as erratic chromosomal behavior and the procedure that is used to determine the levels of 4 pregnancy hormones is known as the triple marker test. Alpha-fetoprotein (AFP) is a protein produced by fetal tissue Human chorionic gonadotropin (hCG) is a hormone produced by the placenta Unconjugated estriol (uE3) is a form of estrogen that is produced by the fetus through metabolism. Inhibin A is a hormone produced by the placenta.

Preparation

Women do not need to prepare for a triple marker screen test. There is no eating or drinking requirements beforehand. Moreover, there are no risks associated with taking the triple marker screen test.

Uses

Low levels of unconjugated estriol help to determine chromosomal or congenital anomalies and have multiple clinical applications. DOWN SYNDROME- Down syndrome is primarily characterized in the fetus of pregnant women possessing a less than normal level of unconjugated estriol.

PLACENTAL INSUFFICIECNY- During the early 1970’s the measurement of urinary estriol was used to decipher fetal wellbeing. Moving forward urine samples were replaced by blood and by the end of 1990 estriol measurement was substantially replaced by biophysical techniques known as ultrasound. However, low levels of estriol have always been a key reflection of placental insufficiency in women.

If the mother is diabetic The mother’s weight If she’s having multiple pregnancies

Procedure

A blood sample is sent to the lab in order to measure levels of pregnancy hormones. The specimen is blood, serum or heparinized plasma. It is advised that blood samples be collected in redtop venipuncture tube while in the case of plasma, evacuated tube(s) containing heparin be used.

Serum samples clot the blood and centrifuging the specimen would result in separation of serum or plasma from the cells. Samples are refrigerated at -8°C for span of 5 days. If the samples are not in a position to be assayed during this interim, then they can be kept at -20°c for 30 days. Avoid usage of contaminated devices. Avoid frequent thawing and repetitive freezing.

Limitations

Single values are almost impossible to interpret; trends in a series of measurements are much more important. May be low in case of placental sulfatase deficiency in the presence of a healthy baby. Other causes of decreased estriol levels include subjects living at high altitudes, anemia, severe liver disease, and a variety of drugs.Estriol may be increased with multiple pregnancy and with oxytocin.It is not reliable in the presence of renal disease.