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Free Estradiol (Serum)

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

This test measures the amount of free (unbound) estradiol, a key hormone in women’s reproductive health and menopause, in your blood.

Quick summary

["Free estradiol helps assess hormone balance and potential reproductive or endocrine health concerns."]

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

Key facts at a glance

LOINC
2240-0
Short code
Estradiol Free SerPl-mCnc
Synonyms
Estradiol Free SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
20
Ref high
400
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82670
SNOMED
300919004
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order a free estradiol test to evaluate symptoms like irregular periods, infertility, or menopausal changes. It can also help diagnose conditions such as polycystic ovary syndrome (PCOS), hormone-related cancers, or hormonal imbalances. Free estradiol is particularly useful because it reflects active hormone levels that aren’t bound to proteins in your blood.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the blood draw if your lab requires it. Wear comfortable clothing and plan to rest for a few minutes afterward. Avoid smoking or caffeine before the test if instructed.

How the Test Works

A blood sample is taken from a vein in your arm. The sample is processed to separate free estradiol from other proteins. Advanced lab techniques (such as immunoassay) detect the hormone’s concentration in your serum.

What the Results Mean

Results are typically reported in picograms per milliliter (pg/mL) or similar units. While reference ranges vary by lab, free estradiol levels can help identify whether your hormone levels are within a healthy range or if further evaluation is needed.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Free Estradiol

Frequently asked questions

How Does Free Estradiol Affect My Health?
Free estradiol plays a critical role in regulating menstrual cycles, bone health, and cardiovascular function. Low levels may indicate hormonal deficiencies, while high levels could signal conditions like ovarian tumors or thyroid disorders. Monitoring free estradiol helps guide treatments for fertility, menopause, or hormone replacement therapy.
What If My Results Are Outside the Normal Range?
If your free estradiol levels are abnormal, your doctor may recommend additional tests (e.g., follicle-stimulating hormone, luteinizing hormone) or further evaluation to determine the cause. Lifestyle adjustments, medications, or other treatments may be suggested based on your overall health picture.
How Often Should I Get This Test?
The frequency depends on your medical history and symptoms. Your provider may suggest periodic monitoring (e.g., every 6–12 months) for conditions like PCOS or perimenopause, but routine testing isn’t standard for all patients.
  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