Free Testosterone (Serum)
This test measures the amount of free (unbound) testosterone in your blood, which is an important hormone for men and women. Free testosterone is the biologically active form of testosterone that can be directly used by your body.
["Understanding your free testosterone levels helps assess hormone balance and potential hormonal health concerns."]
Key facts at a glance
- LOINC
- 96559-0
- Short code
- Testost Free SerPl Calc-sCnc
- Synonyms
- Testost Free SerPl Calc-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- calculated
- 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 testosterone test if you have symptoms of hormonal imbalances, such as irregular menstrual cycles, low libido, fatigue, or unexplained hair loss. It may also be used to evaluate conditions like polycystic ovary syndrome (PCOS), hypogonadism, or androgen-related disorders.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the blood draw if your test is part of a broader hormonal panel. Avoid alcohol and certain medications that could affect hormone levels for 24 hours before testing.
How the Test Works
A small sample of blood is drawn from a vein in your arm. The blood is then processed to separate free testosterone from other hormones and proteins. The lab analyzes the free fraction of testosterone using a sensitive immunoassay method.
What the Results Mean
Results are typically reported as a concentration (in picograms per milliliter, pg/mL, or nanograms per deciliter, ng/dL). While reference ranges vary by lab, lower-than-expected levels may indicate conditions like hypogonadism, while higher-than-expected levels could suggest Cushing’s syndrome or other hormonal excesses. Your provider will interpret results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Free testosterone level
Frequently asked questions
What Are Common Causes of Abnormal Results?
How Often Should I Get This Test?
Can I Adjust My Diet or Lifestyle Before the 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