THYROID
Free T3 (FT3)
The unbound, active hormone your cells actually run on.
Thyroid Test Kit
An at-home blood spot test measuring six thyroid markers, including Free T3, Free T4, TSH, TT4, TPOab, and Tgbn
Get a more detailed picture of your thyroid from home — no lab visit, no waiting room. This at-home blood spot test measures six markers, including Free T3 and Free T4, so you see how much active thyroid hormone is actually reaching your cells — the part tied to your energy, focus, and metabolism. Please note: not available in NY, CA, or MD due to state regulations on at-home lab testing.
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What Makes This Test Different
The Thyroid Test Kit measures six key markers from a single at-home blood spot — including Free T3 and Free T4 — so you see how much active thyroid hormone is actually available to your cells to help regulate energy, focus, and metabolism. That's a fuller picture than most standard testing gives you.
A typical thyroid check looks at TSH alone — but TSH is a signal from your brain to your thyroid, not a measurement of the hormone actively available in your body. It can read as normal in two situations that matter: when your thyroid isn't producing enough T4, and when your body isn't converting that T4 into the active T3 your cells require. This panel measures what TSH can't.
Your results are delivered by email, then you upload them to the HypoHero Coaching App to track them against empirical ranges right alongside your symptoms and daily temperature — so your labs and how you feel come together in one place, where Hero AI can surface insights you might otherwise miss.
What You're Testing
THYROID
Free T4 (FT4)
The unbound, available form of T4, the raw material your body converts into active hormone.
THYROID
TSH
The brain's signal telling your thyroid to produce thyroid hormone.
THYROID
Total T4 (TT4)
Total thyroxine output, a read on overall production.
THYROID
TPO Antibodies (TPOab)
The key marker for autoimmune conditions like Hashimoto's.
THYROID
Thyroglobulin (Tgbn)
A second autoimmune and production marker that, alongside TT4, gives insight into iodine status.
FAQ
Common Questions
It's a simple finger-prick blood spot collection at home — no clinic, no full blood draw. A few drops of blood on the collection card, left to dry, sealed in the prepaid mailer, and sent to our CLIA-certified partner lab. Your complete results come back in an easy-to-read report.
It's a good fit for anyone with hypothyroid symptoms whether diagnosed or not, people managing Hashimoto's who want to track their antibodies, and anyone on thyroid treatment who wants to see the full picture rather than just TSH.
TSH is made by your pituitary, not your thyroid — it's the brain's request for more or less hormone, not a measure of what's reaching your cells. It can read perfectly normal while the hormones downstream are too low, or while your body struggles to convert them. It's like checking the thermostat setting instead of the room's actual temperature — which is why the Thyroid Test Kit measures the hormones themselves, not just the signal.
Your thyroid mostly makes T4, a storage form your body has to convert into T3 — the active hormone your cells run on. "Free" means unbound and usable; most thyroid hormone in your blood is bound to proteins and inactive. Free T4 shows your usable raw material, and Free T3 shows how much active hormone is actually reaching your cells. You can have a normal TSH and decent Free T4 while your Free T3 sits at the bottom — and that gap is often where the symptoms live.
When your body converts T4, it goes one of two ways: into active T3, or into reverse T3, an inactive form that blocks thyroid function. The two paths compete — so the relationship between your Free T3 and Free T4 already tells you how well that conversion is working, which is the real reason most people reach for a reverse T3 test in the first place. The HypoHero app calculates your Free T3 to Free T4 ratio automatically, giving you a direct read on your conversion without a separate rT3 test. (rT3 in isolation is also hard to interpret — it swings with stress, illness, and fasting, and rarely changes what you'd actually do.)
It includes TPO antibodies and Thyroglobulin, the markers associated with autoimmune thyroid conditions like Hashimoto's. Elevated antibodies are one piece of the picture, but a diagnosis is made by your healthcare provider — this kit helps you see and track those markers over time.
Upload them into the HypoHero app's Labs section and you'll see them against the empirical range — the tighter window where people with healthy thyroid function actually tend to feel their best — so a result that reads "in range" on paper but falls outside that window gets flagged. From there you can track your labs alongside your daily temperature patterns and symptoms, and the Hero AI reads your full history to help you spot patterns and connections across everything you've tracked. A single test is one piece; tracked together with your temperature and symptoms over time, it's how you see the Thyroid Deficit more clearly — and track your progress as you work to fix it.
Once the lab receives your sample, results are typically ready in 10–14 business days and delivered securely through email.
It measures six thyroid markers from a single at-home blood spot: TSH, Free T3, Free T4, Total T4, TPO antibodies, and Thyroglobulin. Together they show not just the signal from your brain (TSH), but how much active hormone your body is actually making and converting, plus the antibody markers tied to autoimmune thyroid conditions — the fuller picture a standard TSH-only test leaves out.
A handful of states regulate at-home lab testing more strictly than the rest of the country. New York, California, and Maryland have specific requirements around direct-to-consumer testing — such as requiring a physician's order or in-state lab licensing — that this kit doesn't currently meet. Rather than offer a kit we can't properly fulfill in those states, we've chosen not to sell there for now. If you're in one of these states, we'd recommend talking with your healthcare provider about ordering similar testing locally.