🦋 Thyroid Deep Dive
For everyone · 8 markers · $185.40
with code CAMERON $206.00
Fatigue, cold intolerance, weight change, hair loss, constipation, low mood, or a 'normal TSH' that never explained how you feel. Women are 5–8x more likely to be affected.
🩸 Order this exact panel — 10% off
All 8 markers load into your cart in one click. No doctor's visit, drawn at any Quest location in the US, results by email in about two weeks. Code CAMERON applies automatically.
Add all 8 markers — $185.40 → Open the full Bloodwork Vault →Why this panel
TSH alone is a screening test, not a thyroid workup. It tells you what your pituitary thinks — not how much active hormone reaches your tissues. This panel measures the actual hormones, the conversion step, the antibodies, and the nutrients thyroid function depends on.
What this panel can settle, and by what logic
The argument for buying eight thyroid markers instead of one is that TSH (Thyroid-Stimulating Hormone) answers a pituitary question and three of the other seven answer questions the pituitary cannot be asked.
- Thyroid Antibodies (TPO + TgAb) beside a normal TSH (Thyroid-Stimulating Hormone) separates two futures. A normal TSH with positive antibodies and a normal TSH with negative antibodies are the same number attached to different risks, and only one of them justifies re-testing yearly. This is the discrimination that makes the panel worth more than the $9 screen.
- Free T4 (Thyroxine) with TSH (Thyroid-Stimulating Hormone) catches the pattern TSH alone cannot report. A low TSH with a low free T4 is central hypothyroidism, which is rare and serious and reads as reassuring on a TSH-only report.
- Free T3 (Triiodothyronine) with Free T4 (Thyroxine) is a conversion reading rather than an output reading. Whether it is a conversion problem or a symptom of something else is the question the next section is about.
- Ferritin and Selenium, Blood are on the list as inputs, not outputs. Both are among the nutrients whose supply affects thyroid hormone production and handling Shulhai 2024, and both are cheap to correct.
Vitamin D (25-Hydroxy) rounds it out as an association rather than a mechanism, which is how it should be read.
What it cannot settle, and what would
Reverse T3 is the second most expensive marker on this list at $45, and the one that carries the least actionable meaning. The American Thyroid Association's commissioned review of routine thyroid testing covers TSH, thyroxine and triiodothyronine, and its conclusion even about those three is that standardization has not yet been demonstrated and results from different assays cannot be treated as equivalent Van Uytfanghe 2023. Reverse T3 sits outside that harmonization work entirely, so a number from one laboratory has no defined relationship to a number from another. Worse, the pattern it is sold to detect — low T3 with high reverse T3 — is the signature of non-thyroidal illness syndrome, an adaptation to being unwell or underfed rather than a thyroid disease to be corrected Savvidis 2025.
It cannot see the gland. A goiter, a nodule and a thyroiditis with a tender neck are ultrasound findings. Eight normal results do not exclude a lump, and a lump is the one thyroid problem that occasionally matters urgently.
A single TSH (Thyroid-Stimulating Hormone) is not a thyroid diagnosis, and the miss rate is measured. In pooled data from two randomized trials in older adults with a raised TSH, levels normalized on their own in 60.8% at a median of one year, and in 39.9% of the placebo group even after the elevation had been confirmed on a repeat — which is why that study's own conclusion is that a third measurement may be needed before anyone is treated van der Spoel 2023.
And it cannot say whether treatment will make you feel different. Symptoms overlap almost completely with iron deficiency, anemia, sleep debt and depression. A positive antibody explains the gland; it does not by itself explain the tiredness, and a Ferritin under 30 ng/mL on the same report is the commoner reason Cancado 2025.
Draw conditions that decide whether the money is wasted
This is the only panel in the female-health set where cycle day is not an instruction, and it is worth saying why: estrogen raises thyroxine-binding globulin, which moves TOTAL T4 and T3 around the cycle and on the pill, but this panel measures the FREE fractions, which are buffered against exactly that Al-Bahadili 2024. Four things do matter.
- Biotin off for 72 hours, and it is worse here than anywhere else. Streptavidin-based analyzers run TSH, free T4, free T3 and the antibodies, so a single high-dose hair or nail supplement can push TSH down and free T4 up at once — the exact signature of Graves' disease, produced by a vitamin Li 2020 Al-Bahadili 2024. That is six of these eight results from one capsule.
- Morning, before any levothyroxine dose. TSH runs highest overnight and falls to its trough in the afternoon, and a dose taken before the draw raises free T4 for hours. Between the diurnal swing and ordinary day-to-day variation, one TSH is a sample from your own distribution rather than your set point van der Spoel 2021.
- Not inside 2 weeks of an acute illness. Illness lowers T3 and raises reverse T3 by design, so a panel drawn in that window reports non-thyroidal illness syndrome and gets read as a conversion defect Savvidis 2025. The same applies to a severe calorie deficit.
- This panel has no hs-CRP, so the Ferritin is uncorrected. Ferritin rises with inflammation, and without a concurrent CRP a mid-range value cannot be distinguished from a low one wearing a disguise Cancado 2025. If iron is the real question, buy the panel that includes the CRP.
How you would know it answered your question, and what each pattern means next
Five patterns, and every interval below comes from how long the pituitary or the store takes to move.
- TSH (Thyroid-Stimulating Hormone) above 4 mIU/L with a normal Free T4 (Thyroxine): repeat at 8 to 12 weeks before anything is prescribed. The pituitary needs 6 to 8 weeks to re-equilibrate after any change in supply, and a large share of raised values resolve without treatment van der Spoel 2023.
- Positive Thyroid Antibodies (TPO + TgAb) with a normal TSH: monitor rather than medicate. Annual TSH is the usual interval, and the antibody titre itself does not need repeating once it is positive.
- Low Free T3 (Triiodothyronine) with a normal TSH and free T4 and a high Reverse T3: look outward, not at the thyroid. Recent illness, surgery, a low-calorie diet or overtraining all produce this, and the check is to fix the input and redraw in 8 weeks rather than to treat the ratio Savvidis 2025.
- Low Selenium, Blood: correcting a deficiency is reasonable; supplementing to treat autoimmune thyroiditis is not. The trial evidence is inconsistent, with one overview finding a signal and one systematic review concluding the efficacy data do not support the practice Wang 2023 Qiu 2021.
- Low Ferritin with everything else normal: this is the commonest outcome of a thyroid panel bought for fatigue. Treat it, retest ferritin at 12 weeks, and only re-run the thyroid markers if the symptoms survive a corrected iron store Cancado 2025.
Sources read for these sections
- Van Uytfanghe K, et al. Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status. Thyroid 2023 · PMID 37655789
- Al-Bahadili H, et al. The Complex Web of Interferences with Thyroid Function Tests. Endocrine Practice 2024 · PMID 39477092
- Li D, Ferguson A, Cervinski MA, Lynch KL, Kyle PB. AACC Guidance Document on Biotin Interference in Laboratory Tests. J Appl Lab Med 2020 · PMID 32445355
- van der Spoel E, et al. Incidence and Determinants of Spontaneous Normalization of Subclinical Hypothyroidism in Older Adults. Journal of Clinical Endocrinology and Metabolism 2023 · PMID 37862463
- van der Spoel E, et al. Within-Person Variation in Serum Thyrotropin Concentrations: Main Sources, Potential Underlying Biological Mechanisms, and Clinical Implications. Frontiers in Endocrinology 2021 · PMID 33716972
- Savvidis C, et al. Critical illness-implications of non-thyroidal illness syndrome and thyroxine therapy. World Journal of Critical Care Medicine 2025 · PMID 40880567
- Wang YS, et al. The Effects of Selenium Supplementation in the Treatment of Autoimmune Thyroiditis: An Overview of Systematic Reviews. Nutrients 2023 · PMID 37513612
- Qiu Y, et al. Insufficient evidence to support the clinical efficacy of selenium supplementation for patients with chronic autoimmune thyroiditis. Endocrine 2021 · PMID 33774780
- Shulhai AM, et al. The Role of Nutrition on Thyroid Function. Nutrients 2024 · PMID 39125376
- Cancado RD. Defining Global Thresholds for Serum Ferritin: A Challenging Mission in Establishing the Iron Deficiency Diagnosis in This Era of Striving for Health Equity. Diagnostics (Basel) 2025 · PMID 39941219
The 8 markers — and why each one is here
Ordering the panel tells you your numbers. The protocol tells you what to do with them — why TSH alone misses the conversion step, how to read free T3 against reverse T3, what the subclinical treatment trials actually found, and the biotin interference that fakes Graves' disease on a lab report.
Join Skool — $10/mo →What this panel is ordered to decide
A panel is a set of numbers until it settles something. These are the decisions this one feeds — each links the pathway it belongs to, what that pathway claims, and what its test list is read for.
The one pathway you should never guess at. Normal TSH with low free T3 and high reverse T3 is the classic dieting-induced conversion problem — the metabolic rate has dropped and no appetite suppressant addresses that. Equally: if thyroid is genuinely fine, this whole pathway is money spent on a problem you don't have.
TSH alone is not a thyroid panel. Normal TSH with low free T3 is impaired conversion, and it is the single most common thing missed in fatigue — you need the full set to see it.
Related panels
Frequently asked questions
8 markers: TSH (Thyroid-Stimulating Hormone), Free T4 (Free Thyroxine), Free T3 (Free Triiodothyronine), Reverse T3, Thyroid Antibodies (TPO + TgAb), Ferritin, Selenium, Blood, Vitamin D (25-Hydroxy).
$206.00 before discount, $185.40 with code CAMERON applied automatically. Individual markers add a one-time $10 draw fee. Ordered through Marek Diagnostics and drawn at any Quest Diagnostics location in the US.
No. These are ordered direct-to-consumer through Marek Diagnostics — you order online, walk into a Quest location, and results are emailed to you in about two weeks. No physician visit or insurance required. Not available in NY, NJ or RI.
Morning, before any thyroid medication. Stop biotin 48–72 hours beforehand — biotin causes falsely low TSH and falsely high FT4 on most immunoassays and is a leading cause of misdiagnosis.
Hashimoto's: positive TPO and/or TgAb, TSH creeping up. Poor conversion: normal TSH and FT4 with low FT3 and high rT3 — look at ferritin, selenium and calorie intake. Central hypothyroid (rare, serious): low TSH and low FT4 together.
Where this goes next
This page is how to read the panel. What to DO about each result — the dosing, the order to correct things in, the week-by-week schedule and what to retest — is a lesson inside Skool.