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Testosterone, Free (Serum)

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

This test measures the amount of free (unbound) testosterone in your blood. Free testosterone is the biologically active form of testosterone that can easily enter cells to influence hormone activity.

Quick summary

["Free testosterone helps regulate energy, mood, and sexual health."]

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

Key facts at a glance

LOINC
59240-2
Short code
Testost Fld-sCnc
Synonyms
Testost Fld-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms related to hormone imbalances, such as low libido, fatigue, or irregular menstrual cycles. It could also be part of evaluations for conditions like polycystic ovary syndrome (PCOS), infertility, or hormonal disorders.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood from a vein. Wear comfortable clothing and plan to stay near the testing site for a short time.

What to Expect During the Test

A healthcare professional will insert a small needle into a vein in your arm to draw blood. You may feel a brief pinch or sting, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results are compared to general reference ranges for free testosterone, but individual needs vary. Low levels may indicate hormonal deficiencies, while high levels could signal conditions like Cushing’s syndrome or tumors. Your provider will discuss findings in the context of your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Testosterone

Frequently asked questions

How often should I get this test?
The frequency depends on your health needs. Your provider may recommend testing every few months for ongoing conditions or once during routine checkups if no symptoms are present.
What can affect my test results?
Factors like stress, certain medications (e.g., steroids), alcohol consumption, and timing of blood draw (e.g., morning vs. evening) can influence results. Always follow your provider’s instructions for optimal accuracy.
Is there anything I should avoid before the test?
Avoid smoking, strenuous exercise, or consuming alcohol 24 hours before the test. Some medications (like certain antidepressants or blood pressure drugs) may also affect results—ask your provider if you’re unsure.
  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