Testosterone, Free

Catalog information reviewed: August 24, 2026 by the Sunridge Medical clinical team.

What this laboratory test evaluates

DetailsTestosterone, Free – This test is crucial for diagnosing conditions like hypogonadism in men, particularly when total testosterone levels are borderline low or when certain conditions affect sex hormone-binding globulin (SHBG) levels. It's also used for identifying hyperandrogenemia in women. The test focuses on free testosterone, which is the biologically active portion of testosterone, making up 2% to 4% of the total testosterone in the body. Free testosterone levels are calculated using total testosterone, SHBG, and albumin measurements.

What patients is this test right for?Men with symptoms of low testosterone or conditions affecting SHBG levels, such as obesity, diabetes, liver diseases, or thyroid issues, might need this test. It's also relevant for women with signs of excessive male hormones, like severe acne or unusual hair growth, despite having normal total testosterone levels.

Low Testosterone Symptoms in Men:• Low sex drive
• Fatigue
• Reduced muscle mass
• Depression
• Difficulty concentrating

Hyperandrogenemia Symptoms in Women:• Severe acne
• Unusual hair growth
• Irregular menstrual cycles

What type of sample is required for this test?2.8 mL serum collected in a red-top tube (no gel).

Test Resources https://www.questdiagnostics.com/healthcare-professionals/clinical-education-center/faq/faq290

Additional test information

Men with symptoms of low testosterone or conditions affecting SHBG levels, such as obesity, diabetes, liver diseases, or thyroid issues, might need this test. It's also relevant for women with signs of excessive male hormones, like severe acne or unusual hair growth, despite having normal total testosterone levels.

Collection and processing

• Sample type: Serum
• Fasting: No
• Estimated laboratory processing: Results should be available in 2 – 5 business days after the sample is collected

How Sunridge uses laboratory information

Sunridge considers the medical question, symptoms, history, medications, prior results, and whether the finding could change care before recommending testing. A laboratory result is not interpreted in isolation and does not establish a diagnosis by itself.

Before requesting this test

Availability, collection requirements, eligibility, and processing estimates can change. Sunridge reviews each request and, when appropriate, creates the order through Fullscript. Follow the current instructions supplied with the approved order.