7 Reasons Your Thyroid Is Struggling

The nutrients, stressors, and toxins driving thyroid dysfunction — and what to do about them.

One night I was at the house of a friend having dinner and across the table I noticed his 16-year-old daughter had a mass in her neck, clearly a goiter. I brought it up and asked if they knew about this. They said they had been to an endocrinologist who put her on thyroid medication because her TSH was high. I was shocked that a physician would relegate a young woman to a lifetime of medication when all that was needed was some iodine and possibly other supplements to fix the underlying problem.

Over the years I have had multiple patients with goiter and other thyroid problems who were treated with levothyroxine (generic for Synthroid or T4). Thyroid-related complaints are one of the most common reasons people seek medical care, especially when symptoms such as fatigue, brain fog, weight change, or cold intolerance are involved. As a result, thyroid testing has become routine, and thyroid hormone replacement is prescribed on a massive scale. Levothyroxine, in particular, has remained one of the most frequently prescribed medications for years.[1],[2]

Being among the most prescribed medications is not for nothing, thyroid dysfunction is genuinely common, but the failure is to reduce a complex endocrine issue to a single lab value, TSH, without fully exploring the mechanisms behind a patient’s symptoms. The result is a system in which many people are screened, labeled, and treated, while the underlying causes of thyroid dysfunction is ignored.

Limits of TSH-Based Diagnosis

Much of conventional thyroid diagnosis relies on thyroid stimulating hormone (TSH), which is produced by the pituitary gland in the brain. In standard practice, elevated TSH means that the thyroid is underperforming, while suppressed TSH is overactivity.[3] This may be all the doctors know but it does not paint the whole picture. Many things affect thyroid function, such as:

• Cortisol[4] —Chronic stress suppresses TSH, and high cortisol prevents conversion of the inactive T4 to the active T3.
• Inflammation[5] — Cytokines interfere with TSH signaling, chronic inflammation lowers conversion of T4 to T3, and contributes to autoimmune thyroid dysfunction.
• Caloric restriction — Dieting artificially lowers TSH. If testing is done in a fasted state, the TSH might not be accurate.
• Time of day — TSH can swing 50% between morning and afternoon
• Iodine status, selenium, zinc, iron — All modify TSH independently of thyroid health
• Genetic enzyme status – The enzymes that make T4 in the thyroid gland, as well as the conversion of T4 to T3 are variable, depending on their genetics.

A patient may be told that everything is normal because TSH falls within range, or may be started on medication when TSH is only mildly abnormal, without a complete evaluation of thyroid hormones and endocrine stressors.

Nutrient deficiencies

One major endocrine stressor is nutrient deficiencies. The nutrients that affect thyroid hormone levels are not rare deficiencies.

• Tyrosine is a semi-essential amino acid that is commonly lacking.
• Iodine – the most common cause of goiter is iodine deficiency, which is increasing in the United States.[6]
• Selenium is required for the production of T4, as well as the conversion of T4 to T3.[7]
• Zinc – needed to make T4, conversion to T3, and thyroid receptor proteins.[8]
• Iron – required for TPO enzyme to make T4 and T3 in the thyroid gland.[9]

Goitrogens

The classic raw vegetable goitrogens deserve a mention — including raw cruciferous vegetables (broccoli, kale, cabbage, Brussels sprouts), soy, millet, and even excessive green tea. They inhibit iodine uptake and TPO activity. Cooking largely deactivates them, and iodine sufficiency blunts their effect, but someone juicing raw kale daily while iodine-deficient is stacking the deck against their thyroid. This is actionable and low-hanging fruit.

Toxicity: Halogens and Iodine Competition

The thyroid requires iodine to synthesize T4. Some researchers and clinicians point to halogen compounds such as fluoride, bromide, chlorine, and perchlorate as potential disruptors because they can interfere with iodine uptake or transport. The table below summarizes several commonly cited examples and the ways they are said to affect thyroid physiology.

Element	Source	Effect on Thyroid
Fluoride	Water, toothpaste, Teflon	Blocks iodine uptake; was once used as a drug to suppress hyperthyroidism
Bromide	Flame retardants, bread dough,[10] citrus sodas, tap water, Hot tubs	Displaces iodine
Chlorine	Tap water, pools, cleaning products	Competes with iodine; a highly chlorinated pool might affect your thyroid[11]
Perchlorate	Rocket fuel, fireworks, fertilizers	Potent iodine transport inhibitor — widespread in groundwater[12]

From this perspective, everyday exposure through water, food, household products, and industrial contaminants may place a chronic burden on thyroid regulation, especially in individuals who are already vulnerable because of nutrient deficiencies or autoimmune disease.

PFAS and Hormone Transport

PFAS, often called “forever chemicals,” are another class of compounds frequently discussed in this context.[13] These substances are widespread in the environment and have been studied for possible endocrine effects, including interference with the proteins that transport thyroid hormones in the bloodstream. If those transport systems are altered, circulating lab values may not fully reflect what is happening at the cellular level.

Plastics, BPA and Phthalates

Endocrine-disrupting compounds associated with plastics, including BPA,[14] which can lower T3, and phthalates,[15] which may increase T3. Because these compounds are present in packaging, personal care products, receipts, and other common materials, exposure can be difficult to avoid.

Questions About T4-Only Treatment

Another major point of debate concerns treatment itself. Levothyroxine is T4, the hormone most commonly prescribed for hypothyroidism. It must be converted to T3 to be active. We have already seen that several different things can affect that conversion.

The thyroid naturally produces several hormones, including:

• T4 (~80-90%) — the storage form, largely inactive
• T3 (~10-20%) — the active form that actually runs your metabolism
• T2, T1, calcitonin — other hormones with their own functions

The T3 made by the thyroid gland is only partially used by the body. Most T3 conversion happens in peripheral tissues, meaning the individual cells of your body, which requires:

• Healthy liver function
• Adequate selenium
• Adequate zinc
• Adequate iron
• Low inflammation
• Normal cortisol with a good circadian rhythm
• Normal genetic deiodinase enzymes

 

This may explain why some patients continue to report fatigue, weight gain, brain fog, hair loss, or cold intolerance even after their TSH normalizes on levothyroxine. It also explains why some people feel better on T3, or combinations of T4 and T3 like desiccated thyroid preparations such as Armour or NP Thyroid.

Low T3 Syndrome / Euthyroid Sick Syndrome

In chronic illness, inflammation, or severe stress, the body deliberately downregulates T4-to-T3 conversion and upregulates conversion to reverse T3. This is likely an adaptive, energy-conserving response. The TSH can look normal while free T3 tanks and reverse T3 climbs. Dumping more T4 into this system doesn’t fix it — it often makes things worse by providing more substrate for rT3 production.

Medically Induced Hypothyroidism[16]

Not all thyroid hormone prescriptions are written for spontaneous or naturally developing hypothyroidism. Some are needed because thyroid function has been impaired by medical treatment, surgery, or drug side effects.

• Lithium (for bipolar disorder) — directly damages the thyroid, often permanently
• Amiodarone (for heart arrhythmia) — loaded with iodine, wrecks thyroid function
• Beta Blockers — block the effects of thyroid
• Checkpoint inhibitors (cancer immunotherapy) — can destroy the thyroid
• Radiation to the neck — fries the gland directly
• Thyroidectomy — “we’ll just remove it and give you pills”

Thyroid hormone is necessary for life. In such cases, long-term thyroid replacement may be medically necessary.

The Rise of Autoimmune Thyroid Disease

Hashimoto’s thyroiditis is now the leading cause of hypothyroidism in many developed countries.[17] Because it is an autoimmune condition, the issue is not only hormone deficiency, but also immune dysfunction directed at thyroid tissue. Thyroid disease is not just a problem with the thyroid gland, you must also consider immune and environmental factors.

• Gut permeability (leaky gut) from glyphosate, processed food, and gut-disrupting medications
• Chronic viral load (EBV reactivation is strongly linked to Hashimoto’s)
• Vitamin D deficiency from indoor lifestyles and sunscreen hysteria
• Chronic stress — cortisol dysregulation drives Th1/Th2 immune imbalance
• Environmental immune disruptors — the same chemicals listed above

From a functional perspective, we must find out why the immune system is attacking the thyroid in the first place, rather than just give more thyroid hormone.

How To Evaluate the Thyroid

Rather than just testing the TSH and prescribing permanent hormone replacement, you must find the underlying cause. Everything in the body can be tested. First, start with what is the problem. For example, fatigue is very common, but most often it is not a thyroid problem.

Symptoms are an essential part of the evaluation for low thyroid:[18]

• Fatigue – “I feel like I have to push myself to do anything”
• Cold intolerance – cold hands and feet, wearing a sweater in 80-degree weather
• Constipation – needing laxatives to have a bowel movement
• Hair loss – the eyebrows are common, as well as the hair on the head falling out
• Weight gain – if this is the only symptom, it is not a thyroid problem.
• Dry skin – from lack of sweating

High thyroid (hyperthyroidism) has a completely different set of symptoms:

• Nervousness – feeling like you are constantly being pushed.
• Tremor, or shaking – a fine tremor that does not affect your function (like writing)
• Weight loss – This is highly variable and may not be present
• Sweating (heat intolerance) – going out in the snow with shorts and a t-shirt

Each of these can have multiple cause, but those with multiple symptoms of either low or high thyroid are likely to have these issues.

If the symptoms warrant, the first test is a complete thyroid panel:

• Thyroid Stimulating Hormone (TSH) – pituitary hormone (since it is the hormone that tells the gland to make more, TSH is high when thyroid is low, and low when thyroid is high)
• Free T4 – This is what the thyroid gland mostly makes. It is the reservoir that is in the blood for the body tissues to tap into and make T3.
• Free T3 – this is the active thyroid hormone.
• Reverse T3 – This is like having a left-handed glove when you need a right-handed glove. It is made when there is increased stress, and blocks the active T3. The rT3 Dominance Pattern, causing functional hypothyroidism at the cellular level regardless of what the other numbers say. A common functional cutoff: free T3 (pg/mL) to reverse T3 (ng/dL) ratio below 0.2 suggests rT3 dominance.
• Thyroid Peroxidase Antibodies (TPO) – signals an autoimmune disease, antibodies that attack an enzyme that is needed to make T4
• Anti-Thyroglobulin Antibodies – this is autoimmune antibodies against the carrier protein for the thyroid hormone.

Test for Nutrients using blood or urine tests. I don’t use hair because it has too much environmental exposure. I also think the WBC nutrient tests aren’t reliable.

• Iodine – a common deficiency, especially in the United States.
• Selenium – a common deficiency trace mineral that is hard to get in food in some areas of the world.
• Iron – more common deficiency in women.
• Tyrosine – as we age we digest and absorb less protein.
• Zinc – essential for both thyroid and immune function.
• Copper – must balance with Zinc.
• Vitamin D – Low vitamin D is associated with autoimmune disease

Test the Adrenals – A.M. Cortisol; DHEAS; and possibly plasm metanephrines.

Test for toxins – There are many labs online that will test for environmental toxins, including bisphosphonates, PFAS, and mycotoxins.

Test for Bowel disease/gut flora – there are many labs that test the bowel flora, such as the GI MAP test.

 

The Myth of T4 Forever

So many people are told that they can never stop the thyroid pills. This is simply not true. I have helped many reverse their thyroid problems. The thyroid atrophies when you take thyroid hormones, but the gland can start working again by giving the proper nutrients and gradually lowering the prescriptions. The idea is to allow TSH to increase so it can stimulate the thyroid gland to start making hormones again.

The Deiodinase Polymorphisms

A significant portion of the population carries polymorphisms in the DIO2 gene (the one responsible for peripheral T4-to-T3 conversion). These people literally cannot convert T4 to T3 efficiently — their enzyme is genetically sluggish. They will never feel right on T4 alone, no matter how perfectly the dose is titrated. This isn’t fringe; it’s well-characterized genetics. If you have this problem, T4 will not work for you. You will need to take T3

How To Treat Thyroid Dysfunction

The important thing about treatment is to find the underlying cause first. It is so easy to get into the same rut as the doctors, treating a lab number and not the cause.

DETOX[19]

We are all exposed to lots of halides: fluoride, bromide, and chloride compete with iodide. If you’re bathing in fluoridated water, brominated bread, and chlorinated pools, your effective iodine requirement goes up. If you have thyroid issues, you must start with a halide detox.

First add the basic nutrients:

Selenium — 200 μg/day as selenomethionine or selenium yeast. Without this, the oxidative stress from increased T4​ production and Peroxide​ generation will inflame the thyroid. Selenium also supports glutathione peroxidase, which is critical for neutralizing the oxidative byproducts of halide detox.

Magnesium — 400–600 mg/day.

Vitamin C — 1 gm with each meal, improves iron absorption. Also acidifies urine slightly, which enhances renal bromide clearance.

Unrefined salt (sodium chloride) — The chloride in salt competes with bromide at renal reabsorption sites and supports its excretion. This is why the “salt loading” protocol exists in iodine circles. ½ tsp in water 1–2x daily during active detox phases.

B vitamins (B-complex) — Particularly B2 (riboflavin) and B3 (niacin) for FAD/NAD-dependent detox pathways.

Zinc 15mg per day

After a couple weeks – use 2% Lugol’s solution in sufficient quantities to displace the other halides. The gland preferentially uptakes iodide (I−). Elemental iodine (I2​) has different tissue distribution: breast tissue, prostate, and ovaries. Lugol’s solution provides both forms for a better detox.

Some will have encountered warnings that iodine can trigger or worsen Hashimoto’s: the concern is that excess iodine increases TPO activity and hydrogen peroxide production, and without adequate selenium to run glutathione peroxidase, that oxidative stress can inflame the gland. This is why you front-load selenium and other nutrients before introducing iodine — you’ve already solved for this.

Start low, go slow:

• 1–2 drops of 2% Lugol’s Solution for 2 weeks.
• Next, titrate up slowly to 10 drops (25mg iodine), increasing by one drop per dose.
• Pulse dosing (every other day) is more effective and prevents buildup of excessive iodine
• Continue taking it every other day for 2 weeks.

After the detox, you can continue Lugol’s solution about 2 drops once per week to maintain the iodine sufficiency and prevent halide toxicity. People with long-term bromide exposure (brominated oils) may store it in the fat for months. The chronic detox is gradual.

Other treatments: Anything else will be dictated by the test results. If the problem is in the adrenals, then of course you must deal with stress hormones. If you have autoimmune disease, then you need an immune protocol – repair the bowel, improve nutrition, fix bowel flora, and supplement high-dose vitamin D. If the problem is toxic you will need to detox from that specific toxin.

If the problem is deficiency you will need to supplement the deficient nutrients. I have had many who take multiple thyroid supplements, hoping to improve, but still have symptoms of low thyroid. When we test, we find it is something else, and finally get results. It is so helpful to know what the problem is, so the treatment is not random.

How To Take Thyroid Hormone

The nice thing about thyroid hormones is that every animal with a thyroid gland makes the exact same hormone, however a pig makes the same ratio of T4 to T3 as humans. Cows are different. Sometimes the thyroid gland puts out a lack of hormones so taking a thyroid hormone pill may be necessary. In this case, you find what works best. The tests get you close, but you don’t treat based on numbers exclusively. The primary guide is symptoms. If you are taking too little, you will get the symptoms of low thyroid, and if too much, the symptoms of high thyroid.

I have had patients do best with a T4 prescription. Some people need T3 and T4 to function well. This can be done with a T3/T4 medication (Thyrolar), or a natural thyroid extract (Armour, NP Thyroid, Naturethroid, Westhroid). Thyroid extracts are also found over the counter, but they usually require more pills because they are not concentrated, they are just ground up thyroid glands from pigs or beef.

Thyroid should be taken on an empty stomach because food and medications can interfere with absorption. The common absorption disruptors include: calcium, iron, magnesium, proton pump inhibitors, H2 blockers, and even coffee taken within an hour of thyroid medication. Many patients take their levothyroxine with their morning supplements or coffee and unknowingly reduce absorption by 30–40%. Simple fix, big impact.

The T4-monotherapy crowd treats thyroid dysfunction like it’s a thermostat — tweak one dial, job done. Take this pill, see you in six months. But running a thyroid properly means working backward from the symptoms to find what actually broke the system. Labs inform; they don’t dictate. Symptoms tell you whether the treatment is actually working at the tissue level, not just painting over the numbers.

Thyroid care doesn’t live in a single specialty. It sits at the crossroads of endocrinology, environmental toxicology, nutritional biochemistry, immunology, and the kind of medicine where you actually listen to the patient. If the goal is symptom resolution and long-term metabolic health — not just a TSH value that fits inside a reference range — then the entire conversation has to shift. Stop asking “what pill normalizes the labs” and start asking “why did this person’s thyroid system fail in the first place.”

 

 

Sources:

[1] https://studylib.net/doc/25273389/50-most-commonly-prescribed-medications

[2] https://clincalc.com/DrugStats/Top200Drugs.aspx

[3][3] https://www.thyroid.org/thyroid-function-tests/

[4] https://biologyinsights.com/the-connection-between-thyroid-and-cortisol/

[5] https://www.thyroidschool.com/library/the-thyroid-and-inflammation

[6] https://www.acibademhealthpoint.com/iodine-deficiency-in-the-united-states/

[7] https://link.springer.com/article/10.1186/s43094-026-00972-1

[8] https://link.springer.com/article/10.1186/s43094-026-00972-1

[9] https://thyroidpharmacist.com/articles/balancing-iron-levels-can-help-your-thyroid/#_ftn9

[10] https://www.kingarthurbaking.com/pro/reference/bromate

[11] https://pmc.ncbi.nlm.nih.gov/articles/PMC9326600/

[12] https://www.sciencedirect.com/science/article/abs/pii/S2451965025000201

[13] https://endocrinenews.endocrine.org/exposure-to-forever-chemicals-may-affect-thyroid-health/

[14] https://pmc.ncbi.nlm.nih.gov/articles/PMC7216215/

[15] https://pmc.ncbi.nlm.nih.gov/articles/PMC7216215/

[16] https://www.restartmed.com/medications-thyroid-problems/

[17] https://scienceinsights.org/how-common-is-hashimotos-disease-and-who-gets-it/

[18] https://my.clevelandclinic.org/health/diseases/8541-thyroid-disease

[19] https://www.earthclinic.com/remedies/lugols-iodine-treatment-bill-thompson.html