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Dr. Tyna Moore · 2026-05-14 · Tyna Moore (host), Amie Hornaman

What Doctors Don't Tell You About Your Thyroid | Dr. Amie Hornaman

26 research-tied claims examined: 4 contradicted 7 overstated 4 context 9 supported 2 unverified

4

Contradicted by research

0:31:07Tyna Moore (host)contradictedhigh

The DSM-IV states that if antidepressants do not work, clinicians should consider Cytomel (T3).

"In the DSM-4, when you apply an antidepressant to a patient and it doesn't work—like usually SSRI will be like first line, you may give them an MAO inhibitor, you apply those antidepressants and they'll, you know, they'll stack them sometimes—and it doesn't work, it actually says to consider Cytomel and make sure that you address the T3" (said at 0:31:07)

The host claims that the DSM-IV explicitly directs clinicians to consider Cytomel (triiodothyronine/T3) when antidepressant treatment fails. This statement misrepresents the manual. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) is strictly a diagnostic taxonomy used to classify and define criteria for psychiatric disorders; it does not contain pharmacological treatment guidelines, clinical prescribing algorithms, or medication recommendations. Clinical practice guidelines and clinical trials evaluate T3 augmentation strategies in patients who meet DSM-IV diagnostic criteria for major depressive disorder (e.g., PMID 16483669), but the DSM-IV manual itself does not instruct clinicians to prescribe Cytomel or any other drug.

0:34:10Amie Hornamancontradictedhigh

Eighty to ninety percent of the population has Hashimoto's thyroiditis.

"I think it's safe to say like 80 to 90% of the population has Hashi." (said at 0:34:10)

The speaker's claim that 80% to 90% of the population has Hashimoto's thyroiditis is contradicted by epidemiological evidence. A comprehensive global systematic review and meta-analysis of 48 studies covering over 22 million participants found that the overall adult prevalence of Hashimoto's thyroiditis is approximately 7.5% (95% CI: 5.7% to 9.6%), with regional estimates ranging from 5.8% to 14.2%. Even when considering thyroid autoantibody seroprevalence in general populations, figures remain far below the claimed 80% to 90%.

0:47:18Amie Hornamancontradictedlow

Hypothyroidism or low thyroid function impairs the effectiveness of GLP-1 receptor agonist medications.

"Thyroid's low and slow, GLP-1 won't work. People are wasting money." (said at 0:47:18)

Clinical evidence directly contradicts the claim that hypothyroidism prevents GLP-1 receptor agonists from working. In a retrospective case-control study evaluating weight loss with the GLP-1 receptor agonist liraglutide, individuals with hypothyroidism on stable levothyroxine therapy achieved significant and comparable weight loss relative to matched controls without thyroid disease (-10.8% vs. -8.9%, P = 0.940), with similar proportions reaching ≥5% total body weight loss (79.2% vs. 71.0%, P = 0.248). Baseline TSH levels within the normal reference range did not predict or limit weight loss outcomes.

1:05:07Tyna Moore (host)contradictedhigh

A study showed that women with subclinical hypothyroidism have approximately a 56% increased risk of dying from a heart attack.

"He showed a study in women in particular, if they were subclinical hypothyroid, meaning their labs looked normal, but symptomology was there, like 56% increased risk for dying of a heart attack." (said at 1:05:07)

The speaker misdefines subclinical hypothyroidism and inaccurately characterizes its diagnostic findings. Subclinical hypothyroidism is strictly defined as a laboratory diagnosis in which thyroid-stimulating hormone (TSH) is elevated while free thyroxine (T4) remains within the normal reference range, regardless of symptoms (patients are frequently asymptomatic). It does not mean that lab tests are normal. Regarding cardiovascular risk, major population studies in postmenopausal women, such as the Rotterdam Study (PMID 10681281), found that subclinical hypothyroidism ( elevated TSH with normal free T4) was an independent risk factor associated with an increased prevalence of myocardial infarction (odds ratio 2.3; 95% CI, 1.3 to 4.0) and aortic atherosclerosis (odds ratio 1.7; 95% CI, 1.1 to 2.6). Because the host's claim fundamentally misstates the diagnostic criteria of the condition, the overall assertion is contradicted.

7

Overstated

0:29:06Amie Hornamanoverstatedlow

Impaired thyroid function reduces immune system function and diminishes the body's ability to surveillance and destroy cancer cells.

"So, we know that if your thyroid isn't functioning well, then your immune system isn't even functioning at a top level. So, why did we see, you know, so many people being taken out by COVID when, you know, it's just a virus. It's just a—man-made, but you know, that's a whole other discussion. But, you know what? If your thyroid isn't functioning well, even your ability to surveillance cancer cells, like your body's ability to seek out and destroy the cancer cells that we all have in our body" (said at 0:29:06)

While thyroid hormones do play a role in modulating cellular metabolism, leukocyte function, and adaptive immune responses (including T cell differentiation), the relationship between thyroid status and immune function is complex, bidirectional, and context-dependent rather than a simple on-off switch. Furthermore, asserting that impaired thyroid function impairs cancer immune surveillance across the board is an oversimplification not supported by clinical oncology data; in multiple malignancies, hypothyroidism is actually associated with slower tumor growth or improved responses to immune checkpoint inhibitor therapy, whereas thyroid hormones can sometimes stimulate tumor proliferation and angiogenesis.

0:15:00Tyna Moore (host)overstatedmoderate

Hypothyroidism is associated with and can present as frozen shoulder and tendon tears.

"I mean, you rip a tendon before you're menopausal, I should say, because if you rip a tendon when you're menopausal, I'm going to blame estrogen, too. But you rip a tendon, I'm like, "Thyroid." ... You have chronic thoracic pain, thyroid. You have migraines, thyroid." (said at 0:15:00)

Hypothyroidism has a well-established observational and genetic association with frozen shoulder (adhesive capsulitis). A meta-analysis of 10 case-control studies found that patients with adhesive capsulitis had significantly higher odds of hypothyroidism (OR 1.92) and subclinical hypothyroidism (OR 2.56). However, the claim that premenopausal tendon tears can be broadly attributed to thyroid dysfunction is overstated. While basic science models and case reports suggest thyroid hormone imbalance may alter tenocyte biology and tendon healing, systematic reviews and meta-analyses evaluating major tendon injuries (such as full-thickness rotator cuff tears) find that thyroid disease is not a significant independent risk factor compared to mechanical, anatomical, and age-related factors.

0:15:48Amie Hornamanoverstatedlow

Low thyroid function is a causative factor in migraines and frozen shoulder.

"then I go into those wild and wacky symptoms that you wouldn't necessarily pair up with thyroid like migraines and frozen shoulder that absolutely can be attributed to low thyroid function." (said at 0:15:48)

While observational studies show a significant statistical association and comorbidity between hypothyroidism and migraine (e.g., in a large multinational cohort of over 33 million patients), the relationship is largely correlational and bidirectional rather than a definitive direct cause. Furthermore, evidence linking hypothyroidism directly to frozen shoulder (adhesive capsulitis) is mixed and unproven; a 2025 systematic review and meta-analysis of metabolic and hormonal factors found no significant association between frozen shoulder and thyroid function (SMD 0.067, 95% CI -0.024 to 0.158). Claiming that migraines and frozen shoulder can 'absolutely be attributed to low thyroid function' overstates correlational and conflicting observational findings as established causal relationships.

0:32:13Amie Hornamanoverstatedlow

Functional psychiatry uses T3 to treat conditions like manic depression and schizophrenia due to T3 receptor sites in the brain.

"Functional psychiatry will use T3 even for extreme cases, like manic-depressive and schizophrenia, they will use T3 because of the T3 receptor sites on the brain." (said at 0:32:13)

Triiodothyronine (T3 or liothyronine) augmentation has been studied and used in psychiatry for treatment-resistant affective disorders, including bipolar depression (historically referred to as manic depression), due to the role of thyroid hormones and thyroid hormone receptors in central nervous system neurotransmission and mood regulation. However, systematic reviews note that evidence for T3 in bipolar disorder remains limited, mixed, and based largely on small or open-label studies. Furthermore, there is no established clinical evidence or guideline support for using T3 to treat schizophrenia.

0:33:40Amie Hornamanoverstatedlow

Epstein-Barr virus is a major precursor to Hashimoto's thyroiditis.

"EBV is a huge precursor to Hashimoto's." (said at 0:33:40)

While Epstein-Barr virus (EBV) has been investigated as a potential environmental trigger or cofactor in Hashimoto's thyroiditis and other autoimmune thyroid diseases, describing it as a "huge precursor" significantly overstates the scientific evidence. Observational studies report variable detection rates of EBV in thyroid tissue and blood of Hashimoto's patients, but findings are inconsistent, and controlled studies show no clear causal link or significant difference in viral presence compared to controls. Current consensus views EBV as one of several hypothetical environmental triggers in genetically predisposed individuals, rather than an established major precursor.

0:40:22Amie Hornamanoverstatedlow

Eating gluten triggers molecular mimicry and antibody attacks against the thyroid gland in individuals with Hashimoto's thyroiditis.

"like you said, molecular mimicry, whenever you eat gluten, that's kicking up a thyroid storm. It's kicking up your antibodies basically to attack your thyroid." (said at 0:40:22)

The claim that eating gluten directly triggers acute antibody attacks or a "thyroid storm" via molecular mimicry in patients with Hashimoto's thyroiditis is overstated. While molecular mimicry (such as cross-reactivity involving transglutaminase enzymes) is a hypothesized theoretical link between celiac disease and autoimmune thyroiditis, published clinical studies do not demonstrate that gluten ingestion triggers acute antithyroid antibody surges or thyroid destruction in Hashimoto's patients who do not have celiac disease. Reviews of the scientific literature conclude that evidence is insufficient to recommend a gluten-free diet to non-celiac patients with Hashimoto's thyroiditis. Furthermore, a "thyroid storm" is a specific, life-threatening medical emergency involving severe hyperthyroidism, not a reaction triggered by gluten in Hashimoto's thyroiditis.

0:54:40Tyna Moore (host)overstatedlow

Low thyroid function impairs keratinocyte turnover, leading to cystic acne, keratosis pilaris, rough skin, and ingrown toenails.

"if your thyroid is low, your keratinocytes aren't turning over. So, you end up with cystic acne. You end up with the bumps on the arm. You end up with rough—I I get rough outer thighs. Um, I just get rough skin everywhere. I get that, you know, I've seen dermatologists on Instagram talk about that fishy skin that people get on their shins. ... Ingrown toenails are a thyroid symptom because the keratinocytes around the nail bed won't shed." (said at 0:54:40)

Thyroid hormones are well-established regulators of skin homeostasis, epidermal differentiation, and keratinocyte proliferation. Low thyroid function (hypothyroidism) is known to cause cutaneous changes such as xerosis (dry, rough skin) and acquired ichthyosis (scaling or "fish-scale" appearance on the shins) due to reduced epidermal turnover, barrier alterations, and decreased sweating and sebum production. However, extending this mechanism to claim that hypothyroidism directly causes cystic acne or that ingrown toenails are a thyroid symptom driven by failure of periungual keratinocytes to shed is unsupported. Cystic acne is primarily driven by excess sebum production, follicular hyperkeratinization, microbial colonization, and inflammation, whereas hypothyroidism typically reduces sebaceous gland activity. Similarly, ingrown toenails (onychocryptosis) are primarily mechanical in etiology (such as improper trimming, ill-fitting footwear, or anatomic nail morphology) rather than recognized clinical manifestations of low thyroid turnover.

4

Needs context

0:23:15Tyna Moore (host)needs contextmoderate

T4 can convert into reverse T3 when a person is under high levels of stress.

"the T4 definitely can go to reverse T3 if you're stressed out of your mind like [laughter] I have been." (said at 0:23:15)

Thyroxine (T4) is converted into the inactive metabolite reverse T3 (rT3) through inner-ring deiodination (primarily via type 3 iodothyronine deiodinase). In situations of severe physiological stress—such as critical illness, major surgery, trauma, or severe caloric restriction (a pattern known as nonthyroidal illness syndrome or euthyroid sick syndrome)—active T3 levels decline while reverse T3 levels frequently rise. However, while this metabolic shift is well-documented in major somatic illness and acute hospital settings, evidence that everyday psychological or emotional stress produces a clinically significant conversion of T4 into reverse T3 is limited.

0:29:35Amie Hornamanneeds contextmoderate

Every person has cancer cells continuously present in their body that the immune system constantly destroys.

"the cancer cells that we all have in our body, FYI, we all have them, but your immune system is constantly destroying them." (said at 0:29:35)

The claim states that every person has cancer cells continuously present in their body that are constantly destroyed by the immune system. In immunology and oncology, the framework of cancer immunoediting recognizes an "elimination phase" (or immunosurveillance), in which the immune system detects and destroys nascent transformed cells. Furthermore, genomic sequencing shows that healthy individuals accumulate somatic mutations and clonal expansions in normal tissues throughout life. However, phrasing this as "we all have cancer cells" is a slight oversimplification; histologically normal tissues accumulate driver mutations and altered cells, but possessing mutated or aberrant precursor cells is not clinically or pathologically synonymous with having malignant cancer. The core physiological mechanism of immune elimination (immunosurveillance) acting against newly transformed or aberrant cells is well supported.

0:41:30Tyna Moore (host)needs contextmoderate

Eighty to ninety percent of women diagnosed with hypothyroidism have Hashimoto's thyroiditis.

"and what, like 80, 90% of women with hypothyroidism have Hashimoto's." (said at 0:41:30)

In iodine-sufficient regions, chronic autoimmune thyroiditis (Hashimoto's thyroiditis) is the underlying cause in the vast majority (often estimated between 80% and 90%) of non-iatrogenic primary hypothyroidism, predominantly affecting women. However, globally, iodine deficiency remains a leading cause in iodine-deficient areas, and a substantial minority of hypothyroidism cases arise from iatrogenic causes (such as thyroid surgery or radioactive iodine therapy) and medication side effects.

1:03:56Amie Hornamanneeds contextmoderate

Hypothyroidism causes myxedema, characterized by visible thickening and swelling of the face, neck, skin, and back of the arms rather than just adipose tissue.

"The myxedema, the swollen face, the moon face, the thickening. Like if you're looking at yourself and your your face, like it's not just fat. It's literally like a thickening of the the face, of the neck, of the skin, back of arms. It's it's thicker." (said at 1:03:56)

Generalized myxedema is a hallmark cutaneous manifestation of severe hypothyroidism caused by the accumulation of hydrophilic glycosaminoglycans (notably hyaluronic acid) in the dermis and subcutaneous tissues, which produces non-pitting edema, facial/periorbital puffiness, and skin thickening rather than simple adipose tissue expansion. However, the specific clinical term 'moon face' (moon facies) is classically a feature of Cushing's syndrome (hypercortisolemia) rather than hypothyroidism.

9

Supported by research

0:05:00Amie Hornamansupportedhigh

T4 is an inactive thyroid hormone, whereas T3 is the active thyroid hormone.

"what she gave me is T4. That's the inactive thyroid hormone. There's there's this active thyroid hormone called T3." (said at 0:05:00)

In standard thyroid endocrinology, thyroxine (T4) is classified as a prohormone, whereas triiodothyronine (T3) is the primary biologically active hormone. T4 is secreted by the thyroid gland and converted in peripheral tissues to active T3 via outer-ring deiodination catalyzed by the iodothyronine deiodinase enzymes DIO1 and DIO2. T3 binds to nuclear thyroid hormone receptors with approximately 10- to 15-fold higher affinity than T4 to mediate canonical genomic actions. While emerging research demonstrates that T4 possesses weak intrinsic receptor activity and non-genomic membrane interactions, it primarily serves as a circulating precursor pool for local and systemic generation of active T3.

0:09:39Tyna Moore (host)supportedhigh

Lithium administration causes hypothyroidism.

"And so the lithium on top of it makes you hypothyroid." (said at 0:09:39)

Lithium therapy is well established to cause thyroid dysfunction, significantly increasing the risk of both subclinical and overt hypothyroidism. A comprehensive systematic review and meta-analysis published in The Lancet (McKnight et al., 2012) analyzing randomized controlled trials and observational cohorts found that patients receiving lithium had nearly six times the odds of developing clinical hypothyroidism compared with those receiving placebo (OR 5.78, 95% CI 2.00–16.67, p = 0.001) alongside an average increase in thyroid-stimulating hormone (TSH) of 4.00 iU/mL.

0:17:10Tyna Moore (host)supportedhigh

Conventional laboratory reference ranges define normal TSH levels as anywhere between 0.5 and 5.0 mIU/L.

"Like the TSH that they consider normal is anywhere between 0.5 and 5, basically." (said at 0:17:10)

Conventional laboratory reference intervals for thyrotropin (TSH) in non-pregnant adults typically span approximately 0.4 to 4.0–4.5 mIU/L (with some conventional assays and laboratories using cut-offs up to 5.0 mIU/L). The speaker's statement accurately captures the standard clinical reference range commonly used by clinical laboratories.

0:23:55Tyna Moore (host)supportedmoderate

Natural desiccated thyroid formulations contain a blend of T4, T3, and T2.

"because that's for the people listening, it's a blend. It's a more natural blend of occurring blend, I should say, of T4, T3, and even T2." (said at 0:23:55)

Natural desiccated thyroid (NDT) preparations are manufactured from animal (typically porcine) thyroid glands. Because they are derived from whole glandular tissue rather than synthesized as isolated single molecules, NDT naturally contains a mixture of thyroid hormones and their metabolites, including thyroxine (T4), triiodothyronine (T3), and diiodothyronines (3,5-T2 and 3,3'-T2). Analytical testing using liquid chromatography–tandem mass spectrometry (LC-MS/MS) on thyroid glandular products confirms the presence of quantifiable levels of T4, T3, and T2 metabolites.

0:14:03Tyna Moore (host)supportedlow

Hypothyroidism causes myxedema, a proteinaceous edema visible in tissues under ultrasound.

"I could see it under ultrasound, Amie. I would actually put my ultrasound probe down and I would get this really foggy picture underneath and it was very difficult to really see the layers of the tissues that you should be able to see clearly. And I started asking all of my mentors in the space, like these old guys that have been doing ultrasound-guided injections forever. And I'm like, "Are you guys seeing hypothyroidism on on ultrasound?" And they were like, "What are you talking about?" I'm like, "It's myxedema. It's this proteinaceous edema and it's it's under the probe. I can see it."" (said at 0:14:03)

Hypothyroidism causes myxedema, a non-pitting edema characterized by the deposition of glycosaminoglycans and mucopolysaccharides (protein-carbohydrate complexes) in the skin and subcutaneous tissues. Published ultrasonographic studies of myxedematous skin lesions demonstrate distinct sonographic changes, including increased dermal and subcutaneous thickness, hypoechoic substance accumulation, and blurring/loss of definition of the anatomical boundaries between tissue layers, matching the host's description.

0:36:46Amie Hornamansupportedmoderate

Hashimoto's thyroiditis causes the thyroid gland to appear jagged and smaller on ultrasound imaging.

"Like we can see it on ultrasound. It starts looking like Pac-Man attacked it, like jagged. It gets smaller." (said at 0:36:46)

Ultrasonographic imaging of Hashimoto's thyroiditis (chronic lymphocytic thyroiditis) characteristically demonstrates diffuse parenchymal heterogeneity, hypoechogenicity, and micronodularity/pseudonodularity separated by fibrous bands, which gives the thyroid gland an irregular, lobulated, or 'moth-eaten' appearance. Additionally, progressive autoimmune destruction of follicles and advancing fibrosis often lead to thyroid atrophy (volume reduction/shrinkage) in long-standing disease.

0:40:00Amie Hornamansupportedmoderate

Patients can have autoimmune Hashimoto's thyroiditis with seronegative antibody test results.

"There are conditions—it's called seronegative antibodies—that we'll see a zero, but we know that that person has autoimmunity." (said at 0:40:00)

Published clinical and histopathological studies confirm that autoimmune thyroiditis (Hashimoto's thyroiditis) can occur in the absence of detectable circulating thyroid autoantibodies (anti-thyroperoxidase and anti-thyroglobulin antibodies), a condition recognized in the medical literature as seronegative autoimmune thyroiditis. In these patients, characteristic autoimmune lymphocytic infiltration of the thyroid gland and localized intrathyroidal autoantibody production can be present despite negative peripheral blood antibody assays.

0:44:20Amie Hornamansupportedhigh

Nature-Throid is composed of 80% T4 and 20% T3.

"Dr. Tyna said when she was on Nature-Throid, that's 80% T4 and 20% T3." (said at 0:44:20)

Desiccated thyroid extract (DTE) formulations like Nature-Throid and Armour Thyroid adhere to USP specifications standardized to approximately 38 mcg of levothyroxine (T4) and 9 mcg of liothyronine (T3) per grain (65 mg). This corresponds to a T4:T3 weight ratio of approximately 4.22:1, which equates to roughly 81% T4 and 19% T3 (commonly referred to as an 80/20 ratio).

0:52:44Tyna Moore (host)supportedmoderate

Active skeletal muscle is a major site for the conversion of T4 into active T3.

"And your muscle is a huge conversion site. Active skeletal muscle is a huge conversion site of T4 into the active form of T3." (said at 0:52:44)

Human kinetic and enzymatic modeling indicates that skeletal muscle, via type 2 iodothyronine deiodinase (D2), is the primary tissue responsible for extrathyroidal conversion of thyroxine (T4) into the active triiodothyronine (T3) pool in euthyroid individuals. Furthermore, experimental exercise studies demonstrate that physical activity directly increases D2 expression and enzymatic activity in skeletal muscle, accelerating local T4-to-T3 conversion.

2

No source found (not proven false)

0:30:07Amie Hornamanunverifiedvery low

Elevated reverse T3 and non-optimized thyroid function impair the immune system's ability to destroy cancer cells.

"It's the fact that these poor people on T4 only with elevated reverse T3 and nonoptimized thyroids don't have the immune system working enough to destroy cancer cells." (said at 0:30:07)

No published record matching the claim that T4-only therapy, elevated reverse T3, or non-optimized thyroid status impairs the immune system's ability to destroy cancer cells was located; this does not prove the claim false. While T3 (liothyronine) has been investigated experimentally as a potential small-molecule blocker of the TIGIT/PVR immune checkpoint (PMID: 32894141), there is no established clinical or mechanistic evidence establishing that elevated reverse T3 in patients on T4 monotherapy causes immunosuppression that prevents immune clearance of cancer cells.

0:51:20Amie Hornamanunverifiedvery low

Elevated insulin, elevated cortisol, liver dysfunction, gut dysbiosis, and micronutrient deficiencies drive increased conversion of T4 into reverse T3.

"Well, what are the drivers of reverse T3? Elevated insulin from eating like garbage, elevated cortisol—you're all stressed out and wigged out or you just have environmental stressors that are throwing off your adrenals—your liver, your gut, huge, huge places of conversion. So, how many livers are gunked up? How many guts are messed up? Micronutrient deficiencies. There's so many things that get in the way of that T4 to T3 conversion" (said at 0:51:20)

No published record matching the claim that elevated insulin, elevated cortisol, liver dysfunction, gut dysbiosis, and micronutrient deficiencies drive increased conversion of T4 into reverse T3 was located; this does not prove the claim false.

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.