Quick Facts
- Sample: Blood draw from vein
- Fasting: No fasting required
- Turn-around: 4–6 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Measures biologically active testosterone - Tests only the unbound hormone available to your tissues
- More precise than total testosterone - Especially accurate when binding proteins are abnormal
- No prescription required - Direct access testing with confidential electronic result
- Morning collection recommended - Optimal timing when testosterone levels naturally peak
- Specialist interpretation included - Professional guidance with your results
- Single blood draw - Minimal discomfort with convenient collection sites
Who Is This Test For?
- Men with low testosterone symptoms despite normal total testosterone results
- Women with PCOS concerns or unexplained masculinization symptoms
- Individuals monitoring hormone therapy effectiveness and safety
- People with binding protein disorders from obesity, liver disease, or thyroid conditions
- Those investigating fertility issues or sexual dysfunction causes
- Anyone with borderline total testosterone needing more precise assessment
How It Works – Just 3 Steps
- Order online - No doctor visit required; choose your convenient collection location
- Visit lab for blood draw - Quick venous sample collection, preferably in the morning
- Receive confidential results - Electronic delivery within 4-6 business days with interpretation
FAQ
What makes free testosterone different from total testosterone? Free testosterone measures only the unbound, biologically active hormone (1-2% of total), while total testosterone includes both bound and free forms. Free testosterone better reflects what's actually available to your tissues.
When is the best time to get tested? Morning collection between 6:00-10:00 AM is optimal when testosterone levels naturally peak. No special preparation or fasting is required.
What conditions can affect my results? Obesity, liver disease, thyroid disorders, and certain medications can alter binding proteins, making free testosterone more accurate than total testosterone testing.
How often should I retest? For monitoring therapy, every 3-6 months is typical. For initial diagnosis, retesting may confirm borderline results. Your healthcare provider can recommend appropriate intervals.
Can women benefit from this test? Yes, especially women with PCOS, irregular periods, or unexplained hair growth. Normal female ranges are much lower (1-7 pg/mL) compared to men.
What if my results are abnormal? Consult with a healthcare provider for interpretation. Additional tests like LH and FSH may help determine if the issue is primary (testicular) or secondary (pituitary/brain).
More Details
What is the purpose of this test?
The Testosterone Free Serum Test measures the unbound, biologically active testosterone in your bloodstream that's immediately available to your tissues. Unlike total testosterone tests that measure both bound and unbound forms, this test specifically quantifies the small fraction (typically less than 2%) of testosterone not attached to carrier proteins like Sex Hormone-Binding Globulin (SHBG) or albumin (Endocrine Society, 2018).
This test uses either direct analog enzyme immunoassay or liquid chromatography/tandem mass spectrometry methodology to detect these minute but crucial concentrations. Free testosterone provides critical insights into functional hormone levels that standard tests might miss, especially when binding proteins may be abnormal due to various health conditions.
Who would benefit from this test?
Men experiencing symptoms of low testosterone despite normal total testosterone results would particularly benefit, as would women with suspected PCOS or unexplained masculinization. The test is especially valuable for individuals with conditions affecting binding proteins, including obesity, cirrhosis, and thyroid disorders (Mayo Clinic, 2019).
Those monitoring hormone replacement therapy effectiveness, investigating causes of infertility or sexual dysfunction, and following up on abnormal or borderline total testosterone results should also consider this test. The Massachusetts Male Aging Study found low testosterone prevalence in 25.3% of men aged 40-70 years, making this assessment increasingly relevant (JAMA Network, 2023).
When should I order a Testosterone Free Serum Test?
Consider ordering this test when experiencing symptoms like decreased libido, erectile dysfunction, infertility, fatigue, or unexplained muscle loss, especially if total testosterone tests are borderline or inconsistent with your symptoms. For women, irregular periods, decreased sex drive, or signs of excess male hormones warrant testing.
Male hypogonadism affects approximately 5-10% of men over age 30, increasing to 20-40% in men over 70 years (PubMed Central, 2012). Using total testosterone alone to predict low free testosterone has limitations, with studies showing that total testosterone thresholds miss significant numbers of men with functionally low hormone levels.
How do I interpret the results?
Results are compared to age and gender-specific reference ranges established through extensive clinical studies. Your results will indicate whether your free testosterone levels fall within normal, low, or high ranges for your demographic.
Below reference range:
- What it means: Testosterone deficiency
- Typical action: Consult healthcare provider for evaluation
Within reference range:
- What it means: Normal testosterone function
- Typical action: Continue healthy lifestyle habits
Above reference range:
- What it means: Excess testosterone
- Typical action: Investigate underlying causes
Borderline low:
- What it means: Possible deficiency
- Typical action: Consider retesting and symptom correlation
Reference intervals for healthy adult men typically range from 66-309 pg/mL, with higher values (120-368 pg/mL) in younger men aged 19-39 years (PubMed, 2022).
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No special preparation is typically required for this test. However, for optimal and most accurate results, schedule your blood collection in the morning between 6:00-10:00 AM when testosterone levels naturally peak. Continue taking your regular medications unless specifically instructed otherwise by your healthcare provider.
Maintain normal hydration levels before testing, and inform the collection staff of any medications or supplements you're taking. The blood draw requires one full tube of blood collected from a vein, typically in your arm, with minimal discomfort expected.
How often should I get tested?
Testing frequency depends on your specific circumstances and health goals. Regular monitoring helps track changes over time and treatment effectiveness.
- Initial diagnosis: Confirm with repeat test in 2-4 weeks
- Monitoring hormone therapy: Every 3-6 months
- Ongoing health maintenance: Annually after age 30-40
- Symptomatic changes: As needed when symptoms change
Why early detection matters
Early detection of testosterone imbalances can prevent progression of symptoms and improve quality of life significantly. Low testosterone can contribute to decreased bone density, muscle mass loss, cardiovascular risks, and mental health challenges if left unaddressed.
For women, early detection of elevated testosterone can help identify conditions like PCOS before they lead to fertility issues or metabolic complications. Regular monitoring allows for timely intervention and lifestyle modifications that can naturally support healthy hormone levels.
Related tests you may consider
Total Testosterone Test - Complements free testosterone by measuring both bound and unbound forms, providing broader context for overall testosterone status (Request A Test).
Sex Hormone Binding Globulin (SHBG) Test - Measures the main binding protein for testosterone; particularly valuable when free testosterone is abnormal to determine if binding capacity contributes to imbalance.
Hormone #3 Extreme Blood Test Panel, Men - Measures hormone levels to provide insights into reproductive, adrenal, thyroid, stress response, and insulin health.
