Thyroid Panel (Total T4, Total T3 T3 Uptake, TSH, Free Thyroxine Index)
A multi-marker read on thyroid function that connects fatigue, weight change, and mood to how the gland is actually working.
Consider this test if:
- Fatigue, weight change, cold or heat intolerance, hair thinning, or mood changes with no clear cause
- Palpitations, tremor, anxiety, or unexplained weight loss suggesting an overactive thyroid
- Family history of thyroid or autoimmune disease and you want a functional baseline
- On estrogen or contraceptives, or pregnant, where binding-protein shifts can distort total T4
- Already on thyroid medication and tracking whether your dose is holding levels steady
- HSA/FSA eligible
- Typical results in 1-2 days · Reviewed by a real clinician
Blood draw at 1,400+ lab locations nationwide
How to prepare
- Avoid biotin for at least 3 days before your test.
Video consult with your Care Team
A 1:1 call to discuss your health.
What members say on Trustpilot
What this test is for
This panel evaluates thyroid function from several angles at once: TSH (the pituitary signal that drives the gland), total T4 and total T3 (the circulating hormones), T3 uptake, and the calculated Free Thyroxine Index, which estimates free hormone while correcting for shifts in binding proteins. TSH is the most sensitive screening marker: it rises in hypothyroidism and falls in hyperthyroidism, often before symptoms are obvious. Low thyroid output is commonly linked to fatigue, weight gain, cold intolerance, dry skin, hair thinning, constipation, and low mood, while overactivity drives weight loss, palpitations, heat intolerance, anxiety, and tremor. Because pregnancy, estrogen, and oral contraceptives change thyroid-binding globulin, the Free Thyroxine Index is useful here: it keeps the free-hormone estimate interpretable when total T4 alone would mislead. This is the older index-based approach to thyroid assessment; a direct free T4 (FT4) measurement is the modern alternative if you prefer a measured rather than calculated free-hormone value.
Biomarkers tested
Includes 5 biomarkers, 1 of them calculated from your results
The free T4 index is a calculated estimate of active, unbound thyroxine, correcting for the binding proteins that can distort total T4 readings and give a cleaner read on how much thyroid hormone is actually available to your tissues. Doctors use it as a backup or alternative to direct free T4 when protein levels are shifting, from pregnancy, oral estrogen, liver disease, or acute illness. Low values point toward hypothyroidism, with fatigue, weight gain, cold intolerance, hair thinning, and constipation, while high values point toward hyperthyroidism, with anxiety, palpitations, heat intolerance, and unintended weight loss, and either result is best interpreted alongside TSH.
- Specimen
- Serum or plasma
- Method
- Calculated
- Measures
- Mass concentration
T3 resin uptake doesn't measure thyroid hormone directly. It measures how much binding capacity is left on thyroxine-binding globulin (TBG), the protein that carries thyroid hormone through your blood, by seeing how much added radiolabeled T3 gets picked up by a resin instead of binding to TBG. Doctors pair it with total T4 or T3 to calculate a free thyroxine index, which corrects for conditions like pregnancy, estrogen use, or liver disease that raise or lower TBG and can otherwise make thyroid results look abnormal when actual hormone activity is normal, useful when thyroid symptoms like fatigue, weight change, or temperature sensitivity don't match your TSH.
- Specimen
- Serum or plasma
- Measures
- Number fraction (%)
- Specimen
- Serum or plasma
- Measures
- Mass concentration
Total T4 measures all the thyroxine circulating in your blood, both the small free fraction that acts on cells and the larger portion bound to carrier proteins. Because binding proteins shift with pregnancy, estrogen, and liver or kidney conditions, total T4 can rise or fall without your actual thyroid function changing, which is why it's usually read alongside TSH and free T4 rather than alone. It's most useful for catching those binding-protein effects and rounding out the picture when TSH looks off but the cause isn't yet clear.
- Specimen
- Serum or plasma
- Measures
- Mass concentration
TSH is the pituitary's messenger to the thyroid, signaling it to produce more or less thyroid hormone based on what your body needs. This ultrasensitive assay (detection limit under 0.005 mIU/L) picks up even mildly suppressed levels, making it the sharpest tool for confirming hyperthyroidism and distinguishing it from a normal-low result. It's the marker to check when fatigue pairs with weight change, heat or cold intolerance, anxiety, racing heart, hair thinning, or irregular cycles, and it's just as useful as a baseline or for tracking thyroid medication dosing over time.
- Specimen
- Serum or plasma
- Method
- High-sensitivity assay
- Measures
- Concentration
What you'll learn
Insights that connect the dots. A clinician reads your whole picture, not one result in isolation, connecting family history, past results, and lifestyle into clear next steps.
Your personalized action plan. Nutrition, supplements, and training in one clinician-reviewed protocol, updated as your results change.
Track your trends. Upload results from any lab and see each biomarker trend over time, so you know what is working.
Never miss a recheck. Mito tells you what is worth retesting and when, then reminds you so nothing slips.
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 1-2 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.
What members are saying
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Helped show an overall picture
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Specific and actionable advice
It felt like, for the first time, I had real data guiding me to make meaningful changes and I've definitely noticed the difference.
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Tired of arguing with my PCP
After extensive research, I decided Mito was the best option. The insights were clear and make sense. Mito gave me peace of mind and a path to follow.
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3x the tests for less money
A great alternative to the basic blood work at your local clinic. Love the report card format. Much better value.
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Best $9 a month I spend
The action plan changes every time new results come in. I've actually never had a health company recommend doing less. Refreshing.
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Finally, prices that make sense
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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. It is never a profit on the test itself. Mito makes its money on the membership, not on marking up your tests. Membership is $9 per month or $99 per year, and any applicable lab order or draw fee is itemized before you pay.
Where do I get tested?
Choose an available partner lab at checkout. If your cart contains multiple blood tests, Mito helps consolidate the eligible tests at one lab when possible. At-home kits and scans follow the collection or appointment process shown on their product page.
Is this eligible for HSA/FSA?
Yes. Mito's lab tests are HSA/FSA eligible, so you can pay with pre-tax dollars.
Add the test to your cart and select "Pay with HSA/FSA" at checkout. You'll finish on the secure checkout page of Flex, our HSA/FSA payments partner, and Flex emails you an itemized receipt from notifications@withflex.com for your records.
Most Mito tests are auto-substantiated, so you usually won't need a Letter of Medical Necessity. If your HSA/FSA administrator asks for more, contact us and we'll help.
When will I get my results?
Your results appear in your Mito dashboard after the laboratory completes processing. A clinician then reviews them before your analysis and personalized action plan are finalized. Timing varies by test, and specialty assays and at-home kits may take longer.
Do I need a physician's order?
No. Mito provides the laboratory order when one is required, so you do not need to arrange a separate physician visit before purchasing.
How do availability and prices vary by state?
Available in 48 states and Washington, DC.
| States | Provider | Availability | Member price | Non-member price |
|---|---|---|---|---|
| All states and DC except HI, NJ, NY, and RI | Labcorp | Available | $35.90 | $50.26 |
| NJ and NY | BioReference | Available | $35.58 | $49.82 |
| HI and RI | Not currently available |
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