Why You're Still Hypothyroid Even With Normal Labs (And What to Test Instead)

Join Dr. James Odell for Season 2 of the Science of Self-Healing Podcast! He's the medical and executive director for BRMI, as well as a practicing naturopathic doctor for over 35 years, and he's here to share with you his extensive knowledge of medicine from a different perspective.

The Bioregulatory Medicine Institute

The Science of Self-Healing Podcast

You're exhausted. Your hair is thinning. You can't lose weight no matter what you do. You're cold all the time, your brain feels foggy, and you just don't feel like yourself anymore. So you go to the doctor, convinced something is wrong with your thyroid—and they run a TSH test and tell you everything is "normal." But you're not fine. You know something is off.

Here's the truth: your body might be screaming "hypothyroid" while your labs say "normal." And that's not because you're imagining things—it's because standard thyroid testing was designed to catch advanced disease.

In this episode, we’ll discuss what conventional thyroid testing misses. You'll discover why TSH alone is not an accurate indicator of thyroid health, how your body might be failing to convert T4 into usable T3, what reverse T3 reveals about chronic stress, and why your gut health and oral microbiome might be sabotaging your thyroid function.

You'll learn:

• The 6 thyroid tests you should actually be requesting (beyond TSH)

• How stress, gut dysfunction, and nutrient deficiencies block thyroid hormone from working—even when levels look "normal"

• Why the gut-thyroid connection is one of the most overlooked factors in thyroid health

• The emerging role of short-chain fatty acids and the oral microbiome in thyroid function

• What "optimal" ranges really mean (versus standard reference ranges)

If you've been told your thyroid is fine but you still feel terrible, this episode will validate your experience and give you a clear roadmap for what to test next.

Transcript for: Why You're Still Hypothyroid Even With Normal Labs (And What to Test Instead)

Hello, everyone, and welcome to the Science of Self-Healing podcast. For health and wellness knowledge from a different perspective. Produced by the Bioregulatory Medicine Institute, also known as BRMI. We are your source for unparalleled information about how you can naturally support your body's ability to regulate, adapt, regenerate, and self-heal. I'm your host, Dr. James Odell, the medical and executive director for BRMI, as well as a practicing naturopathic doctor for over 35 years. And remember, this podcast is for informational purposes only and is not intended to be a substitute for the direct care of a qualified health professional who oversees and provides unique and individual care. The information here is to broaden our different perspectives and should not be construed as medical advice or treatment. Let's get started.

Hello everyone and welcome to another episode of The Science of Self Healing. In this episode I will discuss thyroid dysfunction which one of the most common medicated disorders. Thyroid dysfunction often announces itself quietly. It does not always begin with a dramatic collapse in health or a clearly abnormal blood test. Instead, it unfolds gradually through subtle changes that accumulate over time. Energy levels decline without explanation. Sleep becomes less restorative. Hair texture changes, skin dries, digestion slows, and weight begins to shift in ways that feel resistant to effort. Emotionally, people may notice increased anxiety, low mood, irritability, or a sense of mental dullness that was not present before. These symptoms may fluctuate, improve briefly, then return, creating confusion and self-doubt.

When individuals seek medical evaluation, they are frequently reassured that their thyroid labs are normal. While this reassurance is often well-intentioned, it can be deeply invalidating. The patient is left holding two conflicting truths: the lived experience of dysfunction and the external message that nothing is wrong. Over time, this gap erodes trust in the body, the medical system, or both.

The reality is that conventional thyroid testing was designed to identify advanced disease, not early dysfunction, regulatory imbalance, or cellular resistance. Thyroid physiology is far more complex than a single hormone or signaling loop, and many clinically relevant disturbances fall outside standard lab interpretation. To truly understand thyroid health, it is necessary to examine not only hormone levels, but also how the body produces, converts, transports, receives, and responds to those hormones in the context of stress, immunity, nutrition, and inflammation.

The Thyroid: Your Body's Metabolic Control Center

So, let's start by exploring the thyroid as a metabolic regulator, not just a hormone factory. The thyroid gland is often described as the body's metabolic thermostat, yet this metaphor fails to capture its depth of influence. Thyroid hormones regulate mitochondrial activity—and just to clarify, mitochondria are the tiny power plants inside our cells that produce energy—as well as oxygen consumption, glucose utilization, lipid metabolism, protein synthesis, and heat production at the cellular level. Nearly every tissue in the body contains thyroid hormone receptors, which means that thyroid signaling affects cardiovascular health, neurological function, reproductive hormones, digestion, detoxification, and immune balance.

Crucially, the thyroid gland itself does not operate independently. It is embedded within a regulatory network that begins in the brain and extends to the gut, liver, immune system, and endocrine stress response. The hypothalamus, which is a region in the brain that acts as the body's control center, monitors environmental cues such as light, stress, inflammation, and energy availability. It signals the pituitary gland, which then releases thyroid stimulating hormone. The thyroid responds by producing hormones that must be activated and delivered to tissues throughout the body.

At every step in this sequence, interference can occur. When testing focuses narrowly on whether the thyroid gland is producing hormones, it overlooks the many upstream and downstream processes that determine whether those hormones actually perform their intended function.

Why TSH Alone Doesn't Tell the Whole Story

Now, this brings us to an important question: why does TSH reflect signaling, but not cellular thyroid function? Thyroid stimulating hormone, or TSH, has become the cornerstone of conventional thyroid evaluation, largely because it is easy to measure and responds predictably in advanced thyroid disease. However, TSH is a pituitary hormone, not a thyroid hormone. It reflects how the brain perceives thyroid activity, not how tissues are experiencing it.

This distinction matters because the brain prioritizes survival over comfort. During periods of chronic stress, inflammation, infection, trauma, or caloric scarcity, the hypothalamus may intentionally suppress thyroid signaling to conserve energy. In these cases, TSH may remain within range even as metabolic output declines. The body is not malfunctioning; it is adapting.

Also, TSH normal values vary significantly by lab, age, sex, and especially pregnancy, but generally fall around 0.5 to 5.0 mIU/mL (or µU/mL) for healthy adults. However, some experts prefer narrower ranges (0.4-2.5) for optimal health, and pregnancy, old age, or thyroid conditions requiring different target ranges. A higher TSH usually means an underactive thyroid (hypothyroidism), while a lower TSH often signals an overactive thyroid (hyperthyroidism).

Furthermore, TSH follows a circadian rhythm and can fluctuate based on sleep quality, psychological stress, blood sugar stability, and medication use. A single snapshot measurement may miss these dynamics entirely. Individuals can therefore experience hypothyroid symptoms with TSH values that appear unremarkable, particularly when reference ranges are broad and based on population averages rather than physiological optimization.

The Conversion Crisis: When T4 Doesn't Become T3

Moving along, let's discuss the critical role of hormone conversion and peripheral activation. The thyroid gland predominantly produces thyroxine, or T4, which serves as a prohormone—essentially, think of it as an inactive or storage form of the hormone that needs to be converted into the active form to work. T4 must be converted into triiodothyronine, or T3, to exert metabolic effects. This conversion occurs largely outside the thyroid gland, particularly in the liver and intestinal tract, and is mediated by enzymes that are highly sensitive to stress, inflammation, and nutrient availability. Some of these enzymes are selenium dependent, so deficiency of selenium can affect conversion of T4 to T3.

When conversion is efficient, T3 enters cells, binds to nuclear receptors, and initiates gene transcription—which is basically the process where the hormone tells your DNA to produce specific proteins that regulate metabolic activity. When conversion falters, T4 may accumulate in the bloodstream while tissues experience relative hypothyroidism. Standard testing that measures only TSH and total T4 fails to capture this disconnect.

Conversion inefficiency is common in modern lifestyles characterized by chronic psychological stress, disrupted sleep, restrictive dieting, excessive exercise, environmental toxin exposure, and digestive dysfunction. In these contexts, the thyroid gland may be functioning appropriately, but the body lacks the capacity to activate and utilize the hormone it produces.

Reverse T3: The Body's Brake Pedal

In addition to understanding T4 to T3 conversion, we need to consider reverse T3 as a marker of chronic physiological stress. One of the most overlooked aspects of thyroid physiology is the production of reverse T3. Reverse T3 is created when the body diverts T4 away from active T3 production and toward an inactive form that blocks thyroid receptors. This process is not pathological in the short term. It is a protective adaptation designed to reduce metabolic demand during acute stress.

Problems arise when stress becomes chronic. Persistent elevations in cortisol—which is our main stress hormone—along with inflammatory cytokines, which are chemical messengers released by the immune system during inflammation, or oxidative stress signal the body to remain in conservation mode. Reverse T3 accumulates, metabolic signaling is dampened, and individuals experience classic hypothyroid symptoms despite normal or even elevated T4 levels.

Because reverse T3 is rarely tested, this pattern often goes unrecognized. Patients may be prescribed increasing doses of thyroid hormone without addressing the stress physiology driving hormone diversion. In some cases, this exacerbates symptoms by increasing receptor competition rather than restoring metabolic balance.

For those taking T4 medication such as synthroid it is valuable to test both free T3 and reverse T3.

Cellular Resistance: When Hormones Can't Get Through

Next, we need to examine cellular resistance and the illusion of adequate hormone levels. Even when T3 levels are within optimal ranges, thyroid signaling can fail if cells are unable to respond appropriately. Cellular resistance to thyroid hormone occurs when receptor sensitivity is impaired or when intracellular signaling pathways are disrupted. This resistance is often driven by chronic inflammation, insulin resistance, leptin dysregulation—and leptin is a hormone that regulates hunger and energy balance—mitochondrial dysfunction, meaning those cellular power plants aren't working properly, or toxic burden.

In these cases, blood tests suggest adequate hormone availability, yet tissues behave as though they are deprived. Fatigue persists, metabolism slows, and cognitive and emotional symptoms remain unresolved. This pattern mirrors insulin resistance, where glucose is abundant in the bloodstream but unable to enter cells efficiently.

Standard thyroid labs do not measure receptor sensitivity or mitochondrial responsiveness. As a result, this form of dysfunction is often dismissed or misattributed to psychological causes.

The Autoimmune Connection: When Your Immune System Targets Your Thyroid

So now let's talk about autoimmune thyroid disease as a systemic immune condition. The majority of hypothyroid cases in developed countries are autoimmune, with Hashimoto's thyroiditis being the most common presentation. Hashimoto's is a condition where the immune system mistakenly attacks the thyroid gland.

This is often related to toxicological conditions. In autoimmune thyroid disease, the immune system gradually targets thyroid tissue, impairing hormone production over time. However, the autoimmune process often begins long before hormone levels decline.

Thyroid antibodies can be elevated for years while TSH and T4 remain within range. During this phase, individuals may experience fluctuating symptoms as immune activity ebbs and flows. Without antibody testing, this process remains invisible, and the opportunity for early intervention is missed.

Autoimmune thyroid disease is not a failure of the thyroid gland itself, but a manifestation of immune dysregulation. It reflects breakdowns in tolerance, often rooted in gut permeability—which is when the intestinal lining becomes too porous and allows substances to leak into the bloodstream—chronic stress, infections, hormonal imbalances, and environmental exposures. Treating autoimmune thyroid disease requires addressing these upstream drivers rather than focusing solely on hormone replacement.

The Gut-Thyroid Connection: A Two-Way Street

This naturally leads us to understanding the gut–thyroid–immune axis. The gut plays a central role in thyroid health through its influence on hormone conversion, nutrient absorption, and immune regulation. A healthy intestinal environment, meaning a balanced microbiome, supports efficient T4-to-T3 conversion and helps maintain immune tolerance. Conversely, gut dysfunction promotes inflammation and autoimmunity.

One of the key ways gut bacteria support thyroid function is through the production of short-chain fatty acids, or SCFAs. These are beneficial metabolites produced when healthy gut bacteria ferment fiber. SCFAs support immune regulation and help maintain thyroid hormone balance. In people with thyroid disease, we often see a reduction in beneficial bacteria that produce these SCFAs, such as Faecalibacterium and Roseburia, and an increase in inflammatory bacterial species like certain types of Bacteroides and Proteobacteria.

Conditions such as dysbiosis, which is an imbalance in gut bacteria, small intestinal bacterial overgrowth, or SIBO, where bacteria grow excessively in the small intestine, chronic constipation, and increased intestinal permeability, also known as leaky gut, disrupt thyroid physiology in multiple ways. Poor absorption of key nutrients compromises hormone synthesis and activation. Immune exposure to dietary and microbial antigens—which are basically foreign substances that trigger an immune response—fuels antibody production. Inflammatory signaling interferes with receptor sensitivity and mitochondrial function.

Interestingly, recent research has revealed that it's not just the gut microbiome that matters. The oral microbiome—the bacteria in your mouth—can also affect thyroid health, particularly in autoimmune conditions. Chronic oral inflammation and periodontal disease are more common in people with hypothyroidism and may contribute to systemic inflammation that affects the thyroid gland.

Despite this connection between gut health and thyroid function, gut health is rarely evaluated in thyroid care. Patients may cycle through medications while the underlying digestive and immune imbalances persist unaddressed.

Essential Nutrients: The Building Blocks of Thyroid Function

Furthermore, we need to recognize micronutrients as regulators of thyroid expression. Thyroid hormones do not operate in isolation; they require a precise biochemical environment to function effectively. Iodine is necessary for hormone synthesis, yet both deficiency and excess can disrupt thyroid activity. Selenium protects the thyroid from oxidative damage and supports hormone conversion. Zinc influences receptor binding and immune balance. Iron is required for thyroid peroxidase activity—thyroid peroxidase is an enzyme essential for producing thyroid hormones—and vitamin A is essential for receptor activation.

Vitamin D also plays a crucial role in thyroid health. Vitamin D receptors are present in thyroid tissue, and deficiency has been associated with increased risk of autoimmune thyroid disease. While research on vitamin D supplementation for preventing thyroid disease shows mixed results, studies consistently demonstrate that vitamin D can help reduce anti-thyroid antibodies in people who already have autoimmune thyroid conditions.

Deficiencies in any of these nutrients may be subtle and fall within "normal" laboratory ranges while still impairing thyroid signaling. When nutrient status is not evaluated in context, supplementation or dietary modification may be overlooked as therapeutic tools.

Stress: The Hidden Thyroid Suppressor

In addition to nutrition, we must address stress physiology as a primary driver of thyroid suppression. The thyroid is exquisitely sensitive to stress. Chronic activation of the hypothalamic–pituitary–adrenal axis—which is the body's central stress response system connecting the brain to the adrenal glands—alters thyroid signaling at multiple levels. Cortisol suppresses pituitary output, inhibits conversion enzymes, increases reverse T3 production, and reduces receptor responsiveness.

From a biological perspective, this response is protective. When the environment feels unsafe, the body reduces metabolic output to conserve resources. However, in modern life, psychological stressors are persistent rather than episodic. The thyroid remains suppressed long after the original threat has passed.

Addressing thyroid health without addressing stress physiology is fundamentally incomplete. Restoration of thyroid signaling requires creating conditions of safety, nourishment, and regulation within the nervous system.

A More Complete Approach to Thyroid Health

So where does this leave us? We need to move toward a more complete understanding of thyroid health. A comprehensive approach to thyroid health considers hormones, immune markers, nutrient status, gut function, stress physiology, inflammation, and lived experience as interdependent factors. Symptoms are not inconveniences to be dismissed; they are data points reflecting regulatory imbalance.

True thyroid assessment involves pattern recognition rather than isolated numbers. It asks not only whether hormone levels are adequate, but whether the body is able to receive and utilize those signals effectively.

Excitingly, research is now exploring new interventions that target these root causes. Scientists are investigating the use of specific probiotic strains to support thyroid function through the gut-thyroid axis, and in some countries, researchers are even studying fecal microbiota transplantation for autoimmune thyroid conditions. These approaches represent a new frontier in thyroid care that addresses underlying imbalances rather than just managing symptoms with hormone replacement alone.

Comprehensive Testing: What to Ask Your Doctor For

To get a more complete assessment of thyroid function, a healthcare provider may order a panel of tests beyond just TSH:

Free T4 (FT4): This measures the unbound, active thyroxine hormone circulating in the blood.

Free T3 (FT3): This measures the unbound, active triiodothyronine hormone in the blood; this is the hormone that cells actually use.

Thyroid Antibodies: These tests, which include TPOAb—that's thyroid peroxidase antibodies—and TgAb—thyroglobulin antibodies—check for the presence of autoimmune conditions, such as Hashimoto's thyroiditis or Graves' disease, which are common causes of thyroid dysfunction.

Reverse T3 (RT3): In some cases, this test can help identify if the body is converting T4 into the inactive reverse T3 instead of the active T3 hormone.

If you have persistent symptoms of a thyroid condition—such as fatigue, weight changes, mood issues, or temperature sensitivity—but your standard lab results are "normal", discuss comprehensive testing with your doctor or an endocrinologist.

The Bottom Line

In conclusion, if you're experiencing thyroid symptoms but your labs are normal, you're not imagining things. Your body may be responding to stressors, nutrient deficiencies, gut imbalances, or conversion issues that standard tests don't measure.

Effective thyroid care goes beyond TSH levels. It requires looking at the complete picture: comprehensive labs, gut health, stress management, and nutritional support.

If your symptoms persist despite normal labs, advocate for more thorough testing and consider working with a practitioner who understands these deeper connections. The answers are there—sometimes we just need to look beyond the standard approach.

Well, that’s all for today’s podcast. Please join me again in two weeks, and until then, be well. 

Thank you for your time today, and remember that this podcast is made possible by the Bioregulatory Medicine Institute, also known as BRMI, a nonprofit, global, non political, non commercial institute to promote the science and art of bioregulatory medicine. We extend our gratitude to each and every one of you for listening today, and if you haven't already, make sure to visit us at brmi.online. A treasure trove of invaluable information awaits you there. Connect with us across various social media platforms as well. Come and become a member of our thriving tribe. If you've enjoyed today's episode, we invite you to show your support by rating us, leaving us a review, or sharing the podcast within your circle. Our podcast and mission flourish through sharing, and your participation means the world to us. Our organization is sustained by donations, each of which is tax deductible and fuels projects like this. Visit our website, brmi.online, to contribute or simply to explore the wealth of uncensored and impartial information we offer. No contribution is too small. In just two weeks, we'll be back delving into another captivating topic. Until then, we thank you once again for listening. May wellness and wisdom be your path. Be well.

Bioregulatory medicine is a total body (and mind) approach to health and healing that aims to help facilitate and restore natural human biological processes. It is a proven, safe, gentle, highly effective, drugless, and side-effect-free medical model designed to naturally support the body to regulate, adapt, regenerate, and self-heal. BRMI is a non-commercial 501(c)(3) foundation and will expand and flourish with your support. Our goal is to make bioregulatory medicine a household term.

This article is for informational purposes only and is not intended to be a substitute for the direct care of a qualified health practitioner who oversees and provides unique and individualized care. The information provided here is to broaden our different perspectives and should not be construed as medical advice, diagnosis, or treatment.