Testosterone, Free (Serum or Plasma)
This test measures the amount of free (unbound) testosterone in your blood. Free testosterone is the active form of the hormone that can easily enter cells to influence processes like muscle development, bone health, and sex drive.
["Free testosterone helps assess hormone balance and potential hormone-related health concerns."]
Key facts at a glance
- LOINC
- 17689-1
- Short code
- Testost 15M p chal SerPl-mCnc
- Synonyms
- Testost 15M p chal SerPl-mCnc
- 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 Is Done
Your healthcare provider may order a free testosterone test to evaluate symptoms related to hormone imbalances, such as low or high sex drive, irregular menstrual cycles, or signs of hormonal disorders like polycystic ovary syndrome (PCOS) or hypogonadism. It can also be used in fertility evaluations or to monitor treatment for hormone-related conditions.
What to Expect Before the Test
No special preparation is usually needed. You may have a simple blood draw from a vein in your arm. If you’re taking medications that affect hormones, like birth control or certain antidepressants, let your provider know before the test.
What the Results Mean
Results are interpreted based on your age, sex, overall health, and symptoms. While reference ranges can vary by lab, free testosterone levels outside typical ranges may indicate conditions like hormone deficiencies or excesses that need further evaluation.
Possible Causes of Abnormal Results
Low free testosterone levels might be linked to conditions like pituitary disorders, obesity, or chronic illnesses. High levels could result from tumors affecting hormone production or certain medications. Your provider will discuss these findings with you.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free testosterone is crucial for maintaining energy levels, muscle mass, and reproductive health. Abnormal levels may signal underlying health issues that require medical attention, such as thyroid disorders, genetic conditions, or long-term health complications. Regular monitoring can help manage conditions like PCOS or androgen excess.
Short name
Free Testosterone Level
Frequently asked questions
What does a free testosterone test measure?
How is the free testosterone test performed?
Can lifestyle factors affect free testosterone results?
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