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Test Code UE3 Estriol, Unconjugated, Serum

Reporting Name

Estriol, Unconjugated, S

Useful For

A part of the SEQF/ Sequential Maternal Screening, Part 2, Serum and QUAD / Quad Screen (Second Trimester) Maternal, Serum in biochemical second trimester or cross-trimester screening for Down syndrome and trisomy 18 syndrome


A marker of fetal demise


An element in the prenatal diagnosis of disorders of fetal steroid metabolism, including Smith-Lemli-Opitz syndrome, X-linked ichthyosis and contiguous gene syndrome (placental sulfatase deficiency disorders), aromatase deficiency, primary or secondary fetal adrenal insufficiency, and various forms of congenital adrenal hyperplasia


Assessment of preterm labor risk


Epidemiological studies of breast cancer risk in conjunction with measurement of estrone, estradiol, and various metabolites


Assessing estrogen metabolism, estrogen and estrogen-like medications, and other endogenous or exogenous factors impacting on estrogen metabolism in the context of other basic scientific and clinical studies

Specimen Required


Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 0.6 mL

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  90 days

Day(s) and Time(s) Performed

Monday through Friday; 5 a.m.-12 a.m., Saturday; 6 a.m.-6 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Immunoenzymatic Assay

Method Description

The instrument used is the Beckman Coulter UniCel DxI 800. The Access unconjugated estriol assay is a competitive binding immunoenzymatic assay. A sample is added to a reaction vessel with estriol-alkaline phosphatase conjugate, paramagnetic particles coated with goat antirabbit IgG, and polyclonal rabbit antiestriol. Estriol in the sample competes with estriol-alkaline phosphatase conjugate for a limited number of binding sites on the specific anti-estriol antibody. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then the chemiluminescent substrate Lumi-Phos 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of estriol in the sample. The amount of analyte in the sample is determined by means of a stored, multipoint calibration curve.(Package Insert: Beckman Coulter Access Unconjugated Estriol Assay, 2015)

Reference Values

Males: <0.07 ng/mL

Females: <0.08 ng/mL

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
UE3 Estriol, Unconjugated, S 2250-9


Result ID Test Result Name Result LOINC Value
UE3 Estriol, Unconjugated, S 2250-9

Reject Due To


Mild OK; Gross reject


Mild OK; Gross OK