The thyroid–stomach connection.
A clinical investigation guide for adults with Hashimoto's autoimmunity or persistent hypothyroid symptoms on adequate replacement — and the four pathways by which H. pylori has been associated with antibody titres and hormone availability.
A workup for the thyroid that won't settle.
This guide is written for the patient whose TSH is in range but who still feels hypothyroid, or whose antibody titres won't quiet down. It maps four pathways by which an unsuspected H. pylori infection has been associated with thyroid autoimmunity and hormone availability.
It is not a treatment protocol. It is the diagnostic conversation, written down, so the next appointment is more specific than the last.
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i.
The clinical signature of Hashimoto's with persistent symptomsHow the picture differs from primary hypothyroid, central, under-replaced, and pure peripheral conversion patterns.
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ii.
Four pathways the thyroid workup rarely tests forMolecular mimicry, cofactor malabsorption, Th17 skew, levothyroxine absorption — with the evidence tier for each.
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iii.
Why 'TSH in range' doesn't always mean 'thyroid handled'Free T3 / T4, reverse T3, antibody trajectories — what one number obscures.
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iv.
Labs to request beyond a basic panelanti-TPO, anti-Tg, selenium, ferritin, vitamin D — read together.
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v.
Testing options for H. pyloriStool antigen, urea breath test, biopsy — trade-offs, costs, and what each rules in or out.
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vi.
What positivity changesEradication, antibody re-test, hormone re-evaluation timeline — what to expect at 6 and 12 months.
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vii.
A conversation script for the next appointmentThree questions, phrased clinically, that route the workup toward the gastric pathway without overstating the case.
How an unsuspected infection fuels the antibodies.
Thyroid autoimmunity in the presence of H. pylori rarely runs through a single pathway. The guide treats each as testable, with the evidence tier explicit.
Molecular mimicry
Sequence homology between H. pylori virulence factors (CagA) and thyroid antigens (TPO, Tg) drives cross-reactive antibody formation in susceptible hosts.
Cofactor malabsorption
Hypochlorhydria and atrophic gastritis reduce uptake of selenium, zinc, and iron — cofactors required for T4 → T3 conversion and antibody resolution.
Th17 immune skew
Sustained gastric immune activity shifts CD4 T-cell populations toward a Th17 phenotype implicated in thyroid autoimmunity.
Levothyroxine absorption
Adequate gastric acidity is required for consistent levothyroxine absorption. Chronic H. pylori variably affects gastric pH and replacement dose requirements.
Sharper questions. Better appointments.
The guide doesn't replace a clinician. It gives you the language, the labs, and the literature — so the visit is a clinical conversation, not a search.
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Recognise the clinical signature of Hashimoto's with persistent symptoms and how it differs from primary hypothyroid, central, and under-replaced patterns.
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Name the four pathways — mimicry, cofactor depletion, Th17 skew, levothyroxine absorption — by which H. pylori has been associated with thyroid autoimmunity.
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Request the right secondary labs — anti-TPO, anti-Tg, selenium, ferritin, vitamin D — and read them in combination, not in isolation.
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Decide between testing options — stool antigen, urea breath test, biopsy — based on cost, accuracy, and your specific clinical context.
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Bring a structured conversation to your physician — three concrete questions that route the workup toward the gastric pathway without overstating the case.
Three tiers. One rubric. No exceptions.
Every claim in this guide is tagged with one of three evidence tiers. The summary below previews the four claims central to the case for investigating H. pylori in Hashimoto's autoimmunity. The full reference list — sixteen citations — sits at the back of the PDF.
Thyroid · evidence summary
A few honest questions.
Is this medical advice?
No. It is an investigation guide — written to inform the conversation with a clinician. Diagnosis and treatment decisions belong to your physician.
Do I need to buy the testing kit?
No. The guide is content, sold separately from any Welyon product. It covers all three standard testing options — stool antigen, urea breath test, biopsy — and tells you what each costs and how to ask for it through your existing physician or insurer.
What if my labs are 'in range'?
The guide spends a section on this exact situation — what 'in range' obscures, what to look at in combination, and the secondary markers that frequently shift the picture without changing the headline numbers.
Refund policy?
14 days, no questions. If the guide isn't useful, the Lemon Squeezy receipt has a one-click refund link. We track this to keep the guides accountable.
Who wrote it?
The investigation series is authored by Welyon's editorial team and is being reviewed by the scientific advisory board currently in formation. Reviewer names will appear in the front matter of each guide upon confirmation.
Treat the antibodies as a question. Investigate the cause.
40 pages, sixteen citations, four pathways, one clear path to a sharper appointment. PDF, instant download.
FDA disclaimer · Commercial interest
These statements have not been evaluated by the Food and Drug Administration. This guide is for informational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your physician before acting on any information presented here.
Commercial interest disclosure. Welyon produces an at-home H. pylori testing kit and a physician-supervised Foundation Protocol referenced in this guide. The presence of these products is disclosed throughout — including on this page, the guide cover, and in the front matter of the PDF — and does not change the content of the guide. The investigation steps described would apply equally if neither product existed.
Editorial independence. Evidence grading in this guide follows the same three-tier rubric used across the H. Pylori Investigation Series, applied identically regardless of whether the resulting investigation routes a reader toward — or away from — Welyon's products.