Quick Facts
- Sample: Blood draw (serum)
- Fasting: Not required
- Turn-around: 1–6 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- More accurate than total testosterone – measures hormone that actually affects your body
- No doctor visit required – order directly online with 24/7 availability
- Fast, confidential results – secure digital delivery in 1-6 day
- Cost-transparent pricing – upfront costs with no insurance complications
- Better treatment monitoring – ideal for tracking testosterone replacement therapy
Who Is This Test For?
- Men with low testosterone symptoms (fatigue, decreased libido, muscle loss)
- Individuals on testosterone replacement therapy needing monitoring
- People with borderline total testosterone results requiring clarification
- Men over 30 experiencing unexplained energy or mood changes
- Women with excess testosterone signs (hirsutism, irregular periods)
- Athletes wanting comprehensive hormone assessment
How It Works – Just 3 Steps
- Order online – Select your test and complete payment for instant authorization
- Visit lab – Get blood drawn at any participating location near you
- Get results – Receive secure digital results
FAQ
What makes this different from regular testosterone testing? This measures bioavailable testosterone that can actually affect your tissues, not just total hormone levels.
Do I need to fast before the test? No fasting required, though morning collection (8-10 AM) is preferred for accuracy.
How accurate are the results? Uses specialized ammonium sulfate precipitation methodology with high analytical precision.
Can women take this test? Yes, especially helpful for women with signs of excess testosterone production.
How quickly will I get results? Most results available within 1-6 business days through secure digital portal.
More Details
What is the purpose of this test?
The Testosterone Free and Weakly Bound Blood Test measures biologically active testosterone in your bloodstream – the hormone fraction that can actually exert physiological effects on your tissues and organs (Labcorp 2024). Unlike total testosterone tests that measure all testosterone, this assessment focuses specifically on free testosterone (unbound to proteins) and testosterone weakly bound to albumin, which can easily become available for cellular uptake.
This test uses ammonium sulfate precipitation methodology to selectively remove sex hormone-binding globulin (SHBG)-bound testosterone, leaving only the bioavailable portion for measurement. This approach provides crucial insights that total testosterone alone cannot offer, particularly when SHBG levels vary between individuals (Health Matters 2024).
Who would benefit from this test?
This test is particularly valuable for men experiencing symptoms of testosterone deficiency, including unexplained fatigue, decreased sex drive, erectile dysfunction, muscle loss, or mood changes (Mayo Clinic 2024). It's especially important for individuals over 30, when testosterone naturally begins declining 1-2% annually.
Men on testosterone replacement therapy benefit from regular monitoring to ensure treatment effectiveness. The test is also useful for evaluating borderline total testosterone results or when SHBG abnormalities are suspected. Women with signs of excess testosterone production, such as hirsutism or irregular periods, can gain diagnostic clarity from bioavailable testosterone measurement (American Urological Association 2018).
When should I order this test?
Consider ordering this test if you're experiencing symptoms like decreased energy, reduced muscle mass, low libido, mood changes, or difficulty concentrating – especially if you're over 30 years old. The test is most valuable when total testosterone results fall in borderline ranges, requiring more precise hormone assessment.
Schedule testing for early morning (8-10 AM) when testosterone levels are naturally highest. If you're on testosterone replacement therapy, follow-up testing should occur after 2-4 weeks for topical formulations or 3-4 cycles for injectable preparations (AUA Guidelines 2018).
How do I interpret the results?
Bioavailable Testosterone: 131–682 ng/dL (adult males)
- What it means: Normal range
- Typical action: Continue monitoring if symptomatic
Bioavailable Testosterone: Below 131 ng/dL
- What it means: May indicate hypogonadism
- Typical action: Consult healthcare provider
Bioavailable Testosterone: Above 682 ng/dL
- What it means: Elevated levels
- Typical action: Evaluate for underlying causes
Normal ranges may vary between laboratories – always compare results to the specific reference range provided with your test.
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
Schedule your blood draw for early morning (8-10 AM) when testosterone levels peak naturally. Fasting is generally not required, though some laboratories may request 8-12 hours without food. Discontinue biotin supplements at least 72 hours before testing, as they can interfere with results.
Avoid vigorous exercise, alcohol consumption, and smoking on the day of testing. Inform your healthcare provider about all medications, particularly steroids, opioids, or hormone therapies that may affect testosterone levels (Testing.com 2024).
How often should I get tested?
- Initial screening (men over 30): Every 2–3 years
- Testosterone replacement therapy: Every 6–12 months
- Monitoring symptoms: As recommended by provider
- Follow-up for abnormal results: 2–4 weeks for confirmation
Why early detection matters
Testosterone deficiency affects approximately 26.6% of adult men in the United States, representing an estimated 33.1 million individuals (NHANES 2022). The condition contributes to substantial healthcare costs, with economic burden estimated at $190-525 billion over 20 years due to associated cardiovascular disease, diabetes, and osteoporotic fractures.
Early detection enables timely intervention that can prevent progression of symptoms and reduce long-term health complications. More than 60% of men over 65 have free testosterone levels below normal values, yet only about 5% of hypogonadal men receive treatment, highlighting the importance of proactive testing (BUMC Sexual Medicine).
Related tests you may consider
Sex Hormone Binding Globulin (SHBG) Serum Test– Measures the protein that binds testosterone, providing essential context for interpreting bioavailable results and identifying why total testosterone may not reflect hormone activity (WebMD SHBG Guide).
DHEA-Sulfate (DHEAS) Test – Evaluates the precursor to testosterone production and reflects adrenal gland function, helping differentiate between primary testicular dysfunction and secondary causes (MedlinePlus DHEAS).
Comprehensive Metabolic Panel –is commonly used to evaluate nutrient levels, and liver and kidney function. It is a valuable medical tool that offers a comprehensive overview of various bodily functions through multiple measurements.
