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Free Estradiol (Serum/Plasma)

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

This test measures the amount of free (unbound) estradiol, a key hormone involved in female reproductive health and secondary sex characteristics.

Quick summary

["Free estradiol levels help assess hormone balance and potential reproductive or endocrine conditions."]

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

Key facts at a glance

LOINC
14960-9
Short code
Estradiol Free MFr SerPl
Synonyms
Estradiol Free MFr SerPl
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 hormonal health, diagnose conditions like polycystic ovary syndrome (PCOS), evaluate menstrual irregularities, or monitor hormone therapy. It’s also useful in cases of suspected hormone imbalances, fertility issues, or breast cancer screening.

What Does This Test Involve?

You’ll provide a blood sample (serum or plasma) via a simple venipuncture. The test measures the hormone’s concentration in your blood, excluding proteins that might bind to it. Results are typically reported in arbitrary units concentration (ucnc).

What Are Common Reasons for Abnormal Results?

Low free estradiol may indicate hormonal deficiencies, menopause, or certain medical conditions affecting hormone metabolism. High levels could suggest hyperestrogenism, tumors, or other endocrine disorders. Always discuss results with your provider.

How Is This Test Performed?

The test uses a blood sample drawn from a vein in your arm. The sample is processed to separate free estradiol from protein-bound forms. The result reflects only the unbound, biologically active portion of the hormone.

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.

◆Associated findings1

Short name

Free Estradiol

Frequently asked questions

What Does It Mean to Have High/Low Free Estradiol?
Free estradiol is critical for regulating menstrual cycles, bone health, and cardiovascular function. Abnormal levels may signal reproductive disorders, metabolic issues, or conditions requiring medical intervention. Your provider will interpret results in context with your symptoms and other tests.
How Often Should I Get This Test?
Frequency depends on your health needs. Routine checks may be recommended for women with PCOS, those undergoing hormone replacement therapy, or those experiencing irregular periods. Follow your healthcare provider’s guidance.
Can I Fast Before This Test?
No fasting is required for this blood test. However, inform your provider about any medications or supplements you’re taking, as they may affect results.
  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