Testosterone, Free (Dialysis) and Total, MS
The most accurate way to measure the active testosterone your tissues can actually use.
Consider this test if:
- Low libido, fatigue, erectile dysfunction, low mood, or loss of muscle and strength
- A normal total testosterone that does not match your symptoms, or a shifted SHBG from age, obesity, thyroid, or liver conditions
- Investigating hirsutism, acne, irregular cycles, or suspected PCOS in women
- Monitoring testosterone therapy and wanting the most accurate free-fraction measurement
- Wanting a precise baseline before making treatment decisions
- HSA/FSA eligible
- Typical results in 6-10 days · Reviewed by a real clinician
- Drawn at a CLIA/CAP-accredited lab near you ·
Pre-test considerations
Draw the sample in the morning, ideally before 10 am, when testosterone peaks. Levels vary through the day and drop after meals, so an early, consistent collection time makes results comparable over repeat testing. Acute illness and poor sleep can temporarily lower testosterone. If you use testosterone therapy, note your dose and timing relative to the draw, since these strongly affect the result.
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What this test is for
This test reports total testosterone measured by mass spectrometry alongside free testosterone measured by equilibrium dialysis, the reference method for the free fraction. Most circulating testosterone is bound to SHBG and albumin and is unavailable to tissues; free testosterone is the small unbound portion (typically under 2%) that drives libido, energy, muscle mass, mood, and bone density. Measuring both matters because total testosterone can read normal while free testosterone is low, or vice versa, particularly when SHBG is shifted by age, obesity, thyroid disease, insulin resistance, or liver conditions. Low results are investigated in the context of low libido, fatigue, erectile dysfunction, loss of muscle or difficulty building it, low mood, and poor recovery; high results in women are relevant to PCOS, hirsutism, and irregular cycles.
This dialysis-and-mass-spectrometry version directly measures the free fraction rather than estimating it. The related "Free and Total" panels that report SHBG and albumin use a calculated free testosterone, which is cheaper and adequate for many people; this test is the better choice when SHBG is abnormal or when a calculated result does not fit the clinical picture.
Biomarkers tested
Includes 2 biomarkers
Free testosterone is the small unbound fraction, roughly 1-2% of total testosterone, that's actually available to enter cells and act on muscle, brain, bone, and libido. Total testosterone can look normal while free testosterone runs low if sex hormone binding globulin is high, so this is the number that best explains low libido, fatigue, poor recovery, mood flatness, or difficulty building muscle despite training hard. It's also the marker to track if you're on testosterone therapy or optimizing training and body composition, since it reflects the hormone your tissues actually see, not just what's circulating in reserve.
- Specimen
- Serum or plasma
- Measures
- Mass 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 6-10 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.
Everything your health needs,
in one membership
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Every test at our cost
Members pay our cost on every test, with lab fees passed straight through. The full receipt is itemized, never padded.
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Upload past labs and watch your trends over time. Every marker and visit lives in one longitudinal record, so all your care stays together.
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Year-round clinician support
Text anytime and get clinician-reviewed answers. When you want to go deeper, 1:1 consultations are available at affordable rates.
All for $9/month
Order any test or consult without joining. For $9/month, members unlock member prices, trend tracking, and year-round clinician guidance.
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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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