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Unconjugated Estriol

uE3

Test Codes

EPIC: LAB6886, SOFT: UNEST

Department

Special Chemistry

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

• Plasma specimens. 
• Severely hemolyzed, lipemic or icteric specimens. 
• Specimens not collected and processed as indicated. 

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 0.5 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Monday – Friday.
Results available within 24 hours.

Reference Range

Females: Less than 0.08 ng/mL.
Males: Less than 0.16 ng/mL.

Test Methodology

Chemiluminescent Immunoassay.

Interpretation

• Unconjugated estriol (uE3) is the primary estrogen found in pregnancy. Dehydroepiandrosterone-sulfate (DHEAS) is secreted by the fetal adrenal and then converted to uE3 in the placenta. Levels increase during pregnancy and peak at term. The main value of uE3 measurements is in the diagnosis of maternal-fetal diseases.
• uE3 is used as part of 2^nd trimester screening for Down syndrome, where it is lower than in a normal pregnancy. Low levels have also been associated with pregnancy loss, Smith-Lemli-Opitz syndrome (defect in cholesterol biosynthesis), X-linked ichthyosis and contiguous gene syndrome (placental sulfatase deficiency disorders), aromatase deficiency, and primary or secondary fetal adrenal insufficiency. A high uE3 level has been reported in various forms of congenital adrenal hyperplasia.

Clinical Utility

Unconjugated estriol may be useful in the assessment of disorders of fetal steroid metabolism, fetal demise, and is part of the 2^nd trimester screening for Down syndrome.

CPT Codes

82677
LOINC: 2250-9

Contacts

Last Updated

1/13/2023