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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 men’s hormone balance. Free estradiol reflects biologically active hormone levels, as it’s not bound to proteins in the blood.

Quick summary

["Understanding your free estradiol levels helps assess hormone health and potential reproductive or metabolic concerns."]

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

Key facts at a glance

LOINC
2241-8
Short code
Estradiol Free Tiss-sCnt
Synonyms
Estradiol Free Tiss-sCnt
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 (in women), infertility, or hormone-related conditions. It may also be used in monitoring conditions like polycystic ovary syndrome (PCOS), hormone replacement therapy, or menopause-related changes. In men, it can help diagnose conditions affecting testosterone or estrogen balance.

What Does the Result Mean?

Free estradiol levels vary by age, sex, and health status. While reference ranges differ by lab, very high or very low levels may signal underlying health issues. For example, elevated free estradiol could indicate hormonal imbalances or tumors, while very low levels might suggest hormonal deficiencies or thyroid disorders.

How Is This Test Performed?

A blood sample is drawn from a vein in your arm. The serum (liquid part of blood) is then analyzed using an immunoassay method to measure free estradiol concentration. This process typically takes a few days for results to return.

What Can Affect Your Results?

Several factors may influence free estradiol levels, including medications (e.g., birth control, hormone therapies), recent menstrual cycles, stress, and certain medical conditions. For example, oral contraceptives can temporarily alter hormone levels, and chronic illnesses like thyroid disorders may also impact results.

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 a free estradiol test tell my doctor?
A free estradiol test helps assess whether your hormone levels are within a healthy range for your sex and age. High levels may indicate conditions like ovarian tumors, hormonal imbalances, or certain cancers. Low levels could signal hormonal deficiencies, thyroid issues, or other metabolic problems. Your doctor will use these results alongside other tests and symptoms to guide diagnosis and treatment.
How often should I get this test?
The frequency depends on your medical history and symptoms. Women may need monitoring during pregnancy, menopause, or if they have conditions like PCOS. Men may get tested if they experience hormonal symptoms or are undergoing hormone-related treatments. Always follow your healthcare provider’s recommendations.
Can I prepare for this test?
Minimal preparation is needed. Avoid heavy meals before the blood draw, and inform your provider about any medications or supplements you’re taking, as they may affect results. If you’re pregnant or breastfeeding, let your doctor know 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