Bioavailable Testosterone
The testosterone actually available to your tissues, often a truer read than total when SHBG is off.
Consider this test if:
- Low libido, fatigue, low mood, or loss of muscle and strength despite a normal total testosterone
- Conditions that shift SHBG, such as obesity, thyroid or liver disease, or aging
- Setting a baseline before or while on testosterone therapy
- Investigating androgen symptoms when standard testosterone results are ambiguous
- HSA/FSA eligible
- Typical results in 2 days · Reviewed by a real clinician
- Drawn at a CLIA/CAP-accredited lab near you ·
Pre-test considerations
Draw in the morning, ideally before 10 a.m., when testosterone peaks. Fasting is not required. Recent illness, poor sleep, intense exercise, and testosterone or DHEA supplements can shift the result, so note any hormone products and their timing.
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What this test is for
Bioavailable testosterone is the fraction of testosterone that is either free or loosely bound to albumin, meaning it can act on tissues. It is calculated from total testosterone, SHBG, and albumin, which makes it more informative than total testosterone when SHBG is high or low (common with aging, obesity, thyroid disease, liver disease, or estrogen exposure). This is the test to use when symptoms point to low testosterone but total testosterone reads normal: low libido, fatigue, low mood, reduced muscle mass, poor recovery, and erectile difficulty in men, or unexplained androgen symptoms in women.
The related Free and Total panel reports directly measured free testosterone alongside total, while the Free Androgen Index is a simpler SHBG-based ratio. Bioavailable testosterone is the right default when you want the active-plus-albumin-bound pool quantified, especially when SHBG is the confounder.
Biomarkers tested
Includes 4 biomarkers
Albumin is the protein your liver churns out in the largest quantity, and it does double duty: it holds water inside your blood vessels (so fluid doesn't leak into tissue) and ferries hormones, fatty acids, and medications through your bloodstream. Low albumin points to liver disease, kidney protein loss, chronic inflammation, or poor nutrition, and often shows up alongside swelling, fatigue, or unexplained weight loss. Because it reflects both liver production and overall protein status, it's a useful baseline check and a quick way to see whether inflammation or malnutrition is quietly dragging your protein reserves down.
- Specimen
- Serum or plasma
- Measures
- Mass concentration
- Specimen
- Serum or plasma
- Measures
- Mass concentration
SHBG is a liver-made protein that binds testosterone and estradiol, controlling how much hormone is free to act on tissue rather than locked up in transit. High SHBG (common with high estrogen, hyperthyroidism, or liver disease) can leave you hormonally starved even when total testosterone looks normal, while low SHBG (seen with insulin resistance, obesity, or hypothyroidism) inflates free hormone activity. Pairing SHBG with total testosterone gives you an actual free testosterone picture, useful for investigating low libido, fatigue, mood changes, or irregular cycles, and for tracking how weight loss or metabolic changes are shifting your hormone availability over time.
- Specimen
- Serum or plasma
- Measures
- Substance concentration
Total testosterone measures the hormone your testes (or ovaries and adrenal glands in women) produce to drive libido, muscle mass, bone density, energy, and mood. Low levels show up as fatigue, low sex drive, harder recovery from training, mood changes, and difficulty building or keeping muscle, while high levels in women can signal PCOS or point to an androgen-secreting source. It is the standard baseline for anyone tracking hormonal health with age, evaluating symptoms, or checking response to training, weight loss, or testosterone therapy.
- Specimen
- Serum or plasma
- Measures
- Mass concentration
What to expect
- 1 Book instantly
Click, book, done. Choose a convenient lab location near you. Transparent, up-front pricing.
- 2 Quick lab visit
Testing to fit your busy schedule, usually 15 minutes or less. Walk-in and appointments available.
- 3 Typical results in 2 days
Your results post straight to your dashboard as soon as the lab completes them.
- 4 Expert guidance
Included with Mito membership. A clinician reviews your results and your personalized action plan follows, with clear next steps.
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Frequently asked questions
View all FAQsHow does pricing work?
Every test shows the member price next to the standard non-member price, so you can see what membership saves you. The member price is our cost — covering the lab and what it takes to run the service — never a profit on the test itself; Mito makes its money on the $9 membership, not on marking up your tests. Membership is $9/mo, and you still pay the lab’s order fee. Prices are itemized before you pay, with no hidden fees.
Where do I get tested?
Choose a partner lab (Quest, Labcorp, or BioReference) at checkout. If your cart spans multiple tests, we consolidate the whole order onto a single lab so you only make one visit.
Is this eligible for HSA/FSA?
Yes. This test is HSA/FSA eligible, and you can pay with your HSA/FSA card at checkout.
When will I get my results?
Your results post to your dashboard once your lab completes them, then a clinician reviews them and your full analysis and personalized action plan (with clear next steps) follow. Turnaround varies by test: specialty assays and at-home kits take longer, and each test shows its expected turnaround before you buy.
Do I need a doctor’s order?
No. Mito provides the lab order for you, so you can book and get tested without a separate doctor visit.
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