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- Pregnancy, Estriol
- Unconjugated Estriol
Evaluate fetal distress and placental function in the management of patients facing complications such as preëclampsia, fetal growth retardation, diabetes, Rh immunization, choriocarcinoma, and hydatidiform mole. May be elevated in hydrops fetalis in the presence of a dying fetus. May be low in the presence of a living anencephalic fetus.
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.1 Estriol may be increased with multiple pregnancy2 and with oxytocin.2 It is not reliable in the presence of renal disease.1,2
Immunochemiluminometric assay (ICMA)
Central 95% Range
3.4 to >13.3
3.7 to >13.3
4.3 to >13.3
5.3 to >13.3
6.2 to >13.3
7.4 to >13.3
8.1 to >13.3
8.5 to >13.3
Estriol, E3, is synthesized in the placenta from 16-α-hydroxydehydroepiandrosterone of fetal origin. Thus, normal production can serve as a measure of the integrity of the fetoplacental unit. Sequential monitoring of estriol in high-risk pregnancy has made possible early intervention and fetal salvage. Chronically low estriol values are found in intrauterine growth retardation but also are sometimes seen in normal pregnancy. A decreasing trend is indicative of fetal distress. The sensitivity and specificity of this test for detecting fetal distress are very poor; thus its use for this purpose has been largely abandoned.
Combined evaluation of unconjugated serum estriol, maternal serum hCG, maternal serum AFP, and maternal age has value in predicting risk for fetal chromosomal abnormalities during pregnancy. The use of maternal serum AFP, hCG, and estriol predicts 65% of Down syndrome, as opposed to 28% if only serum AFP is used.3-5
0.3 mL (Note: This volume does not allow for repeat testing.)
If a red-top tube is used, transfer separated serum to a plastic transport tube. All specimens should be drawn at the same time of day to allow comparison of values.
Causes for Rejection
State weeks of gestation on the test request form. This assay is usually performed as a serial measurement.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|004614||Estriol, Serum||2251-7||004614||Estriol, Serum||ng/mL||2251-7|