Testosterone
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Lab test
What is free testosterone, and how does it differ from total testosterone?
Free testosterone is the small fraction of testosterone not bound to SHBG or other proteins, while total testosterone counts it all. Labs often calculate free testosterone from total testosterone and SHBG. ARUP Laboratories lists a calculated free testosterone of 47 to 244 pg/mL for men aged 18 and older; other methods use other ranges.
What does the free testosterone test measure?
SHBG binds tightly to testosterone and carries it in an inactive form. The SHBG test helps explain the gap between total testosterone and how much the body can actually use. Testing.com
ARUP calculates free testosterone from total testosterone and the binding constant of testosterone and SHBG. ARUP Laboratories
Why is the free testosterone test ordered?
- When symptoms such as low libido or erectile dysfunction do not match a total testosterone result. Testing.com
- In people with conditions that change binding proteins, where total testosterone alone can mislead. Testing.com
What are typical free testosterone ranges?
ARUP Laboratories publishes calculated free testosterone intervals for adult males. ARUP Laboratories
Reference ranges differ between laboratories and testing methods, and many also differ by age, sex, pregnancy or the phase of the menstrual cycle. The range printed on your own report is the one that applies to your result, and a clinician interprets it alongside your history.
| Age | Reference interval |
|---|---|
| 16 to 17 years | 38 to 173 pg/mL |
| 18 years and older | 47 to 244 pg/mL |
For females and children, ARUP recommends a different free testosterone test based on mass spectrometry, with its own ranges. ARUP Laboratories
What can affect free testosterone results?
- Anything that shifts SHBG, such as thyroid disease, liver disease, oral estrogen or pregnancy, changes how much testosterone is free. Testing.com
- The method matters: ARUP calculates free testosterone from an immunoassay total testosterone, and recommends a mass spectrometry based test for females and children. ARUP Laboratories
When should you talk to a clinician about a free testosterone result?
- Free testosterone is interpreted with total testosterone, SHBG and symptoms; ask the clinician who ordered it which method the lab used. Testing.com
DiscoverMedica explains what a test measures and what named sources publish. It does not interpret individual results; the clinician who ordered your test, or one you choose, does.
Where can you get a free testosterone test?
A clinician can order it as part of routine or follow-up care. Some services also let you order lab tests yourself; check that a service’s panel includes this marker, which laboratory runs it, and who reviews the result with you.
- Function HealthAnnual membership for broad lab panels, drawn at Quest sites or at home.
- Quest HealthOrder individual lab tests from Quest Diagnostics online, without a doctor’s visit.
Free Testosterone Test: questions, answered
What is a normal free testosterone level for men?
ARUP Laboratories lists a calculated free testosterone of 47 to 244 pg/mL for males aged 18 and older. Labs that measure free testosterone by other methods use different ranges and sometimes different units, so compare a result only with the range printed on the same report.
Is free testosterone more accurate than total testosterone?
It answers a different question. Total testosterone includes testosterone bound to SHBG, which the body cannot readily use; free testosterone estimates the unbound share. Testing.com notes free testosterone and SHBG help when symptoms do not fit a total testosterone result. Which result matters more for a given person is a clinician’s call.
How is free testosterone calculated?
ARUP calculates it from total testosterone and SHBG using the binding constant between them. Some labs measure it directly by equilibrium dialysis instead. Because methods differ, results from different labs are not interchangeable. Ask the lab or clinician which method was used before comparing two results.
Sources
- ARUP Laboratories: Testosterone, Free (Adult Males) (test 0070111)
- Testing.com: Sex Hormone Binding Globulin (SHBG) Test
Last reviewed October 7, 2026. Every source above was checked on or before that date. Educational information only, not medical advice; it does not replace a conversation with a licensed clinician. DiscoverMedica does not employ clinicians.
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