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Urinary Estriol-to-Creatinine Ratio

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

A urine test that measures estriol relative to creatinine, helping evaluate estrogen production during pregnancy.

Quick summary

["This test may help assess placental estrogen production when interpreted with other prenatal screening results."]

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

Key facts at a glance

LOINC
30510-2
Short code
Estriol/Creat Ur
Synonyms
Estriol/Creat Ur
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

Estriol is a form of estrogen produced during pregnancy, mainly by the placenta. This test measures estriol in urine and compares it with urine creatinine, which helps account for differences in urine concentration.

Why might I need this test?

The estriol-to-creatinine ratio may be used as part of prenatal screening to help evaluate placental function and fetal estrogen production. It is usually interpreted together with other screening tests and clinical findings rather than used by itself.

How is the test performed?

A urine specimen is collected as directed by your prenatal care provider. The laboratory measures estriol and creatinine and calculates their ratio.

How do I prepare for the test?

Follow your clinician's urine-collection instructions exactly, including any specified collection period or timing. If a timed collection is requested, record the total urine volume and keep the container closed and labeled as instructed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A lower-than-expected ratio may be associated with reduced placental estrogen production and can occur with placental insufficiency or certain fetal conditions. Interpretation depends on gestational age, urine collection method, medications, and other prenatal screening results, so an abnormal result does not confirm a complication.

Short name

Estriol/Creatinine Ratio, Urine

Frequently asked questions

Is this the same as a routine urine pregnancy test?
No. A pregnancy test detects human chorionic gonadotropin, while the estriol-to-creatinine ratio measures estrogen production and is used for prenatal evaluation.
Does the test require a 24-hour urine collection?
It depends on the order and laboratory protocol. Some collections are timed, while others may use a specified urine sample, so follow the instructions provided by your clinician.
Can an abnormal result mean my baby has a health problem?
An abnormal result may warrant additional evaluation, but it does not diagnose a specific condition by itself. Your clinician will interpret it with gestational age, ultrasound findings, and other screening tests.
  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