Estriol (E3) Blood Test
An estriol test measures E3, one of the three main estrogens the body makes. Estriol is present in small amounts most of the time and becomes far more prominent during pregnancy, when the placenta produces it.
About this test
The body makes three principal estrogens: estradiol, estrone, and estriol. Estradiol is the most active form during the reproductive years, estrone becomes relatively more prominent after menopause, and estriol is the form most associated with pregnancy.
That production pathway is what makes estriol interesting to clinicians. Because it depends on both the placenta and the fetus, it is one of the markers used in certain prenatal evaluations, always as part of a set rather than on its own.
Who might consider this test?
- Never read as an answer by itself
- The timing of the sample within pregnancy matters a great deal to what it means
Test details
| Quest code | 34883 |
|---|---|
| Methodology | Chromatography/Mass Spectrometry |
| Sample type | 0.5 mL serum |
| Collection | Quest patient service center |
Related tests and panels
Measures Anti-Mullerian Hormone (AMH), a hormone associated with ovarian reserve.
Quest resources
Additional details
How estriol differs from estradiol and estrone
Estradiol is the most biologically active estrogen and the one most often measured in fertility, cycle, and menopause conversations. Estrone is the form that becomes relatively more prominent after menopause. Estriol is weaker in activity and normally present in modest amounts, rising substantially only in pregnancy.
Because the three behave differently, they are not interchangeable on a lab order. Ordering the wrong one produces a result that does not address the question being asked, so it is worth confirming with a clinician which estrogen fits your situation before testing.
Estriol in pregnancy
During pregnancy, estriol production reflects a shared pathway between the placenta and the developing baby. That is why it is included in certain prenatal marker panels, where it is evaluated together with other substances and with gestational dating rather than assessed individually.
Because pregnancy dating drives interpretation, an estriol measurement without an accurate gestational age is difficult to make sense of. An obstetric clinician reviews the full set of results in that context and explains what, if anything, warrants follow-up.
Preparation and collection
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides. Mention any hormone medication, hormonal contraception, or supplement you take, since these can influence estrogen measurements generally.
The draw itself takes a few minutes at a patient service center, and most locations accept in-persons during open hours. Your report is delivered to you securely once the laboratory has finished.
Ordering and pricing
The cash price shown beside the order button covers the laboratory work and the physician's order. There is no insurance claim to file, no referral to track down, and no membership. If you are pregnant and being followed by an obstetric clinician, it is sensible to coordinate any hormone testing with them so results land in the right hands.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What is estriol?
Estriol, or E3, is one of the three main estrogens. It circulates at low levels most of the time and is produced in much larger amounts by the placenta during pregnancy.
How is estriol different from estradiol?
Estradiol is the most active estrogen and the one usually measured for cycle, fertility, and menopause questions. Estriol is a weaker estrogen that becomes prominent mainly in pregnancy, so the two are ordered for different reasons.
How much does an estriol test cost?
The cash price is displayed next to the order button on this page and includes the physician's order. No insurance is billed and no separate visit fee applies.
Do I need to fast before this test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides. Follow any preparation instructions your ordering clinician provides, especially if other tests are collected at the same appointment.
Can an estriol result stand on its own?
Not in most situations. In pregnancy it is evaluated as part of a group of markers with accurate gestational dating, and outside pregnancy it is generally reviewed alongside other estrogens by a clinician.