Testosterone, Free (Serum)
This test measures the amount of free (unbound) testosterone in your blood. Free testosterone is the active form of the hormone that your body uses.
["Free testosterone helps regulate energy, mood, and sexual function."]
Key facts at a glance
- LOINC
- 47943-6
- Short code
- Testost 2D p 5000 U HCG IM SerPl-mCnc
- Synonyms
- Testost 2D p 5000 U HCG IM SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84702
- SNOMED
- 275917004
- 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 Is Done
Your doctor may order a free testosterone test to check for hormonal imbalances, especially if you have symptoms like low libido, fatigue, or changes in body hair. It’s also used in conditions like hypogonadism (low testosterone) or polycystic ovary syndrome (PCOS). Free testosterone is particularly important for diagnosing issues in men and women with hormone-related disorders.
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 a loose shirt for easy access to your arm.
How the Test Is Done
A healthcare provider will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood is then sent to a lab for analysis.
What the Results Mean
Results are compared to general reference ranges for your age, sex, and health status. Low free testosterone may indicate hormonal deficiencies, while very high levels could signal conditions like Cushing’s syndrome or tumors. Your doctor will interpret results in the context of your symptoms and medical history.
Reference range
Non-pregnant: <5 mIU/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Free testosterone
Frequently asked questions
What does free testosterone measure?
Can free testosterone levels change with age?
Is fasting required for this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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