Functional medicine collects a whole-health approach to wellness and disease prevention, with a focus on treating the root causes of illness and symptoms. Through a functional medicine lens, we consider the interconnectedness of various physiological systems and the influence of lifestyle factors, including stress, on overall well-being.
The thyroid gland is a small, butterfly-shaped gland in the front of the neck. Despite its small size, thyroid function is critical in metabolism, energy production, body temperature regulation, growth and development, heart function, bone health, and more. Cortisol, the primary stress hormone, increases the metabolic burdens of the body and thus can affect thyroid function.
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Thyroid Function Basics
Understanding thyroid anatomy and physiology allows clarity in the stress-thyroid relationship. The hypothalamic-pituitary-thyroid (HPT) axis system regulates thyroid hormones. The hypothalamus works as the control center in the brain, producing thyrotropin-releasing hormone (TRH) in response to signals from the body. In response, the pituitary gland releases thyroid-stimulating hormone (TSH) into the bloodstream. Then, the thyroid gland produces the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
Thyroxine (T4) is produced in larger quantities and is the metabolically inactive form, while triiodothyronine (T3) is produced in smaller quantities and is the metabolically active form. T4 is converted to the active form of T3 by various tissues and cells in the body. Thyroid hormones play a crucial role in the metabolic processes of every cell in the body by influencing the rate at which cells convert nutrients into energy. They interact with and influence the function of other hormones in the body including insulin, reproductive hormones, and cortisol.
Stress and Cortisol: The Body’s Response Mechanism
Cortisol is produced by the adrenal glands during a stress response. Similarly to the complex neuroendocrine negative feedback loop system in thyroid hormone regulation, the production of cortisol is regulated by the hypothalamic-pituitary-adrenal (HPA) axis system.
In cortisol regulation, the process begins in the hypothalamus where corticotropin-releasing hormone (CRH) is released into the bloodstream after signals from bodily processes. In the pituitary gland, adrenocorticotropic hormone (ACTH) is produced as a response to corticotropin-releasing hormone (CRH). With the release of adrenocorticotropic hormone (ACTH), the adrenal glands are stimulated to produce cortisol. Cortisol is released into the bloodstream through this mechanism in a stress response, whether it is emotional, physical, or psychological.
When the body perceives stress and the fight-or-flight response is activated, cortisol will prioritize essential physiological functions needed for survival to conserve energy. Non-essential bodily functions will be suppressed, such as digestion, immune responses, and reproductive function.
The Cortisol-Thyroid Connection
Chronically elevated levels of cortisol lead to complex interactions between these two feedback loop systems that may impair thyroid function, disrupt the secretion of thyroid hormones, worsen symptoms of thyroid disorders, and worsen autoimmune thyroid conditions.
The following are the bodily effects of the cortisol-thyroid interaction:
- Effects on thyroid hormone conversion: Cortisol can influence the conversion of inactive thyroid hormone T4 to the metabolically active form of T3 in peripheral tissues. Cortisol inhibits the activity of enzyme 5’-deiodinase which is the enzyme that converts T4 to T3. As a result, there is less availability of metabolically active hormones to be used by cells.
- Thyroid dysregulation through the HPT axis: Cortisol can affect the activity of thyroid hormones in the HPT axis. It can inhibit the release of thyrotropin-stimulating hormone (TSH) from the pituitary gland, thereby decreasing the stimulation of the thyroid gland to produce thyroid hormones.
- Acute stress response and thyroid dysregulation: Acute stress may temporarily suppress thyroid function and reduce thyroid hormone levels. As discussed earlier, during times of acute stress cortisol will appoint precedence to send energy toward essential functions, and away from non-essential functions including thyroid hormone production.
- Chronic stress and thyroid dysregulation: Chronic stress can dysregulate the HPA axis and disrupt the balance of cortisol secretion. Chronic elevations of cortisol can be seen in mood and adrenal dysfunction disorders. Chronic disruptions in thyroid function may lead to conditions such as hypothyroidism (or a metabolically under-active thyroid) or hyperthyroidism (or a metabolically over-active thyroid gland).
- Impact on thyroid autoimmunity: Cortisol’s immunosuppressive and anti-inflammatory effects can influence the immune system's response to thyroid antigens. This can lead to the progression of autoimmune disorders such as Grave’s disease and Hashimoto’s disease. The results of this study suggest stressful life events are a precipitating factor in the onset of Grave’s disease.
Diagnosing Stress-Related Thyroid Issues
From a functional medicine perspective, diagnosing thyroid issues linked to cortisol imbalances involves a comprehensive evaluation of a patient's history, symptoms, clinical exam, and laboratory testing. The following are key considerations in diagnosing thyroid issues related to cortisol imbalance in functional medicine.
Past medical history and symptoms evaluation: A thorough evaluation of a patient's medical history, family medical history, and lifestyle factors including stressors, exercise, and dietary habits is recommended initially. A functional medicine provider will be sure to address symptoms that may be related to a cortisol imbalance such as fatigue, mood and sleep disturbances, weight gain, and brain fog along with thyroid dysfunction symptoms such as fatigue, changes in weight, hair loss, temperature intolerance and changes in bowel habits.
Comprehensive testing: A functional medicine provider may order comprehensive testing if they are considering thyroid and/or adrenal dysfunction.
Thyroid function tests are vital in diagnosing thyroid issues. Testing for evaluation of thyroid function includes thyroid-stimulating hormone (TSH), free thyroxine (T4), free triiodothyronine (T3), revere T3 (rT3), and thyroid antibodies (anti-thyroid peroxidase antibodies and anti-thyroglobulin antibodies).
Adrenal function tests analyze cortisol and DHEA through saliva, urine, or blood tests. Salivary cortisol testing measures cortisol levels multiple times throughout the day and may be particularly helpful for providers in assessing cortisol rhythm and adrenal function. Cortisol normally peaks in the morning with a gradual decline throughout the day. A lack of a morning spike or the presence of an evening spike, for example, may show a provider there is adrenal dysfunction.
Evaluate management of stress levels: 75-90% of all human diseases are related to the HPA axis stress response system. It is crucial to assess patient stress levels and lifestyle factors that contribute to chronic stress. A functional medicine provider discusses stress management and relaxation techniques along with lifestyle modifications.
Comprehensive functional health assessment: In functional medicine, providers evaluate the interconnectedness of various physiologist systems to decide the underlying root causes which may address gut health, nutrient deficiencies, hormone imbalances, and mold and toxins.
Functional Medicine Strategies for Managing Stress and Supporting Thyroid Health
Functional and integrative providers prioritize lifestyle modifications such as regular physical activity and movement, obtaining adequate sleep, including regular self-care activities, and sustaining work-life balance. Interventions to balance cortisol levels naturally are a great place to start.
Stress management techniques will vary among patient preferences, and trialing a few different methods is encouraged. Functional providers may recommend practicing mindfulness meditation, deep breathing exercises, yoga, tai chi, muscle relaxation with massage, and nature walks.
Functional medicine prioritizes nutritional support interventions, emphasizing diets consisting of colors of the rainbow including vegetables, fruits, whole grains, lean proteins, healthy fats, and omega-3 fatty acids.
A functional medicine provider may recommend certain adaptogenic herbs or supplements in a patient’s treatment plan to support the body in adapting to stressors, supporting adrenal function and thyroid health.
- Ashwagandha: Research shows that Ashwagandha can have a positive effect on the function of the endocrine system by improving the function of the thyroid gland and supporting adrenal activity.
- Magnesium: Magnesium is an essential nutrient that supports adrenal and thyroid health with its role in regulating stress responses and thyroid hormone synthesis. Magnesium deficiencies disrupt the HPA axis system. Magnesium-rich foods include nuts, seeds, whole grains, leafy green vegetables, legumes, and dark chocolate.
- Pantetheine: Pantetheine is a derivative of pantothenic acid or vitamin B5. Vitamin B5 is referred to as the “anti-stress vitamin”. It plays a critical role in the synthesis of coenzyme A (CoA), which is essential for numerous bodily processes including metabolism. Pantetheine is found naturally in foods such as dairy products, eggs, whole grains, and legumes.
- L-theanine: L-theanine is an amino acid found primarily in tea leaves and is best known for its calming and relaxation effects. Studies have shown theanine relieves psychological stress through its effect on the HPA axis system. It may promote a more balanced cortisol rhythm.
- Rhodiola: Rhodiola Rosea is an adaptogenic herb that supports the body’s resilience to stress.
- Holy Basil: Holy basil is a traditional Ayurvedic adaptogenic herb that is best known for its role in cortisol regulation through enhancing the central nervous system.
- Siberian Ginseng: Siberian Ginseng is a considerable option for those undergoing chronic stress due to its role in modulating cortisol.
Future Directions in Research and Treatment
Scientists continue to explore the stress-thyroid connection and the relationship between stress, the HPT, and HPA axis systems to support future treatment advancements in thyroid and adrenal health.
Maternal stress has been found to affect fetal growth and development. Stress experienced by the mother activates her HPA axis causing a greater release of cortisol that enters fetal circulation. The effects on immune, metabolic, cardiovascular, and reproductive health as an adult can be destructive. You can find more about this study here.
Clinical studies are evaluating the efficacy of stress management activities such as yoga and meditation. The inclusion of these simple activities in a daily routine can have significant implemental effects on the prevention or reversal of symptoms or illness. Research is evaluating the efficacy of stress management techniques and mind-body practices in reducing stress, improving adrenal health, and optimizing thyroid function. This study shows us that a single session of yoga is effective in reducing acute stress.
Ongoing research in the stress-thyroid link deepens our understanding of the complex interconnectedness of the physiologic processes between stress, thyroid health, neuroendocrine regulation, and immune function. The multi-disciplinary approach in functional medicine allows effective interventions in individuals with stress-induced thyroid dysfunctions.
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Key Takeaways
Understanding the stress-thyroid link is essential for optimizing health as well as mitigating thyroid disorder treatments. Understanding the cortisol-thyroid interaction is important for functional medicine providers because it influences various physiological processes in the body.
It is important to remember that this flight-or-flight response system is activated no matter the type of stressor, whether you are in true physical danger or enduring emotional stress. Chronic firing of this fight-or-flight response due to chronic stress may lead to chronic symptoms and even disease, and a stress management discussion with patients is imperative. Working with a functional medicine provider may help discover the root cause of symptoms, thereby improving patient outcomes.
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