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Estriol, Serum or Plasma Mass Concentration

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of estriol, a form of estrogen, in your blood. Estriol is often evaluated in pregnancy to assess fetal health.

Quick summary

["Estriol helps monitor fetal development and placental function during pregnancy."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
2248-3
Short code
Estriol Amn-mCnc
Synonyms
Estriol Amn-mCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What Is Estriol Used For?

Estriol is primarily measured to evaluate the health of your fetus and the function of your placenta. Low levels may indicate potential complications, such as reduced fetal growth or placental insufficiency. High levels can sometimes suggest certain medical conditions or treatments affecting estrogen metabolism.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is then sent to a lab for analysis using a specialized technique to measure estriol concentration.

What Are Common Causes of Abnormal Results?

Results may vary based on pregnancy stage, underlying health conditions, or medications. For example, estriol levels can be lower in early pregnancy or if there are issues with fetal development. Always discuss any abnormal results with your healthcare provider.

When Might This Test Be Ordered?

Your healthcare provider may recommend this test during pregnancy, particularly in the third trimester, to monitor fetal well-being. It may also be used in cases of suspected placental or fetal complications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Estriol Level

Frequently asked questions

Why do some people need to know their estriol levels during pregnancy?
Estriol is a key marker for assessing fetal lung maturity and placental function. Low levels may signal risks like preterm labor or fetal distress, prompting further evaluation or interventions.
What does a low estriol level mean?
A low estriol level could indicate potential complications such as reduced placental function, fetal growth restriction, or other pregnancy-related risks. Your provider will interpret results in the context of your overall health and pregnancy.
Can estriol levels be affected by medications?
Yes, certain medications or conditions (e.g., diabetes, thyroid disorders) may influence estriol levels. Always inform your healthcare provider about all medications or supplements you’re taking before the test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy