Estriol (E3)

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Category:

Turnaround Time: 2 - 4 days
CPT Code:

82677

Test Type: 1 mL Serum
Stability Time:

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3
Reference Range:

Gestational Week

Median

(ng/mL)

Central 95% Range

(ng/mL)

27

4.6

2.6−7.1

28

4.7

2.6−7.8

29

5.0

2.6−8.6

30

5.5

2.7−9.6

31

6.1

2.9−11.0

32

6.9

3.2−12.7

33

8.0

3.4 to >13.3

34

9.3

3.7 to >13.3

35

11.3

4.3 to >13.3

36

>13.3

5.3 to >13.3

37

>13.3

6.2 to >13.3

38

>13.3

7.4 to >13.3

39

>13.3

8.1 to >13.3

40

>13.3

8.5 to >13.3

Overview:

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

Estriol, E3, is synthesized in the placenta from 16-a-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

1. Catanzarite VA, Perkins RP, Pernoll ML. Assessment of fetal well-being. In: Pernoll ML, Benson RC, eds. Current Obstetric & Gynecologic Diagnosis & Treatment 1987. Norwalk, Conn: Appleton & Lange;1987:279-302.

2. Speroff L, Glass RH, Kase NG. Clinical Gynecologic Endocrinology and Infertility. 4th ed. Baltimore, Md: Williams & Wilkins;1989.

3. White RS 3rd. Down syndrome: Current screening techniques. South Med J. 1989 Dec; 82(12):1483-1486. PubMed 2480649

4. Heyl PS, Miller W, Canick JA. Maternal serum screening for aneuploid pregnancy by alpha-fetoprotein, hCG, and unconjugated estriol. Obstet Gynecol. 1990 Dec; 76(6):1025-1031. PubMed 1700348

5. MacDonald ML, Wagner RM, Slotnick RN. Sensitivity and specificity of screening for Down syndrome with alpha-fetoprotein, hCG, unconjugated estriol, and maternal age. Obstet Gynecol. 1991 Jan; 77(1):63-68. PubMed 1701526

Bashore RA, Westlake JR. Plasma unconjugated estriol values in high-risk pregnancy. Am J Obstet Gynecol. 1977 Jun 15; 128(4):371-380. PubMed 868934

Bennett DB, Wells DJ. Endocrinology. In: Bishop ML, Duben-VonLaufen JL, Fody EP, eds. Clinical Chemistry: Principles, Procedures, Correlations. Philadelphia, Pa: JB Lippincott Co;1985:307-343.

Collection Details:

Patient Preparation:

Patient usually in third trimester of pregnancy.

Collection Instructions:

State weeks of gestation on the test request form. This assay is usually performed as a serial measurement.

Red-top tube or gel-barrier tube.

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.

Refrigerate.