Free Testosterone (Serum)
This test measures the amount of free (unbound) testosterone in your blood. Free testosterone is the biologically active form of testosterone that circulates freely in your bloodstream.
["Your doctor may order this test to assess hormone balance, especially if you have symptoms related to testosterone levels."]
Key facts at a glance
- LOINC
- 70240-7
- Short code
- Testost Free SerPl DL<= 3.47 pmol/L-sCnc
- Synonyms
- Testost Free SerPl DL<= 3.47 pmol/L-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 100
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- detection-limit-pmol-l
- CPT
- 83721
- SNOMED
- 113079007
- 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
A free testosterone test helps evaluate hormone health, particularly in men and women experiencing symptoms like low libido, fatigue, irregular periods, or unexplained hair loss. It may also be used in fertility evaluations or to monitor conditions like polycystic ovary syndrome (PCOS) or hypogonadism.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if your blood is drawn in the morning. Wear comfortable clothing and plan to stay for about 15 minutes while a blood sample is taken.
What to Expect During the Test
A healthcare provider will insert a small needle into a vein in your arm. You may feel a slight pinch, but the procedure is quick. The blood sample is then sent to a lab for analysis.
What the Results Mean
Results are compared to general reference ranges, but individual needs vary. Low free testosterone may indicate hormonal imbalances, 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
Optimal: <100 mg/dLN/A
Fasting for 12-14 hours preferred. Water is permitted. Avoid alcohol for 24 hours before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free testosterone levels are critical for reproductive health, muscle mass, bone density, and mood regulation. Abnormal results may prompt further testing for underlying conditions like pituitary disorders, adrenal insufficiency, or genetic disorders affecting hormone production. It can also guide treatment decisions for hormone therapy or management of conditions like PCOS or infertility.
Short name
Free testosterone level
Frequently asked questions
How often should I get this test?
What causes low or high free testosterone levels?
Can lifestyle changes affect my 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