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The Interplay Between Thyroid, Adrenal, and Sex Hormones in Functional Medicine

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The Interplay Between Thyroid, Adrenal, and Sex Hormones in Functional Medicine

The connection between thyroid, adrenal, and sex hormones is vital for managing health and diseases effectively. These hormones work together to control bodily functions like metabolism, stress response, and reproduction. 

This article will help to teach you about the detailed connections between thyroid, adrenal, and sex hormones - helping to set you up with both detailed and foundational knowledge to better treat imbalances in your patients. 


The Thyroid-Adrenal Axis: A Foundational Interplay

The thyroid and adrenal glands help to manage your body's hormone levels and how you respond to stress. They communicate through the thyroid-adrenal axis, part of the body's broader communication system that includes the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-thyroid (HPT) axes. These systems work together to regulate processes like stress response and metabolism.

The thyroid gland controls your metabolism, or how your body uses energy, by releasing thyroid hormones. The adrenal gland produces cortisol, a hormone that helps you handle stress. When you're under a lot of stress for a long time, your adrenal gland makes more cortisol, often resulting in adrenal fatigue. In addition, high levels of cortisol can interfere with the thyroid gland's ability to work properly. For example, it can affect the conversion of thyroid hormones, which can disrupt your metabolism and energy levels.

Further changes in thyroid function can impact the adrenal gland and vice versa. For instance, conditions that attack the immune system can harm both glands at the same time, leading to hormone imbalances. Maintaining the balance between these glands is an important part of optimizing health, affecting everything from how you feel day-to-day to how well you can respond to stress (31). 

Sex Hormones and Their Influence on Thyroid and Adrenal Function

Estrogen, progesterone, and testosterone intricately influence both thyroid and adrenal health, playing pivotal roles in the body’s hormonal balance. 

Estrogen's effect extends to modulating adrenal function by enhancing the adrenal gland's responsiveness to ACTH, thereby boosting cortisol production. It also impacts cortisol's metabolism and plasma concentration by affecting its liver clearance rate. This modulation of the hypothalamic-pituitary-adrenal (HPA) axis by estrogen can lead to increased production of adrenal corticosteroids. In the thyroid, estrogen increases the production of thyroid-binding globulin (TBG) in the liver, which binds more thyroid hormones and reduces their availability, potentially leading to hypothyroidism symptoms, especially under conditions of elevated estrogen levels such as pregnancy or hormone therapy.

Progesterone, often seen as estrogen's natural counterbalance, calms the HPA axis, potentially reducing cortisol levels and influencing the synthesis of adrenal hormones like cortisol and aldosterone. It enhances the sensitivity of the thyroid gland to Thyroid Stimulating Hormone (TSH), facilitating increased thyroid hormone production and the conversion of T4 to the more active T3 hormone. This action helps maintain thyroid hormone levels even with the rise in TBG due to estrogen, highlighting progesterone's balancing effect on both adrenal and thyroid functions. Furthermore, progesterone's modulation of GABAergic transmission in the central nervous system indirectly affects the HPA axis and adrenal hormone production. 

Testosterone exhibits an inhibitory effect on the HPA axis, reducing the secretion of corticotropin-releasing hormone (CRH) from the hypothalamus and ACTH from the pituitary gland, which in turn decreases cortisol production by the adrenal glands. This mechanism aligns with the observed lower cortisol responses to stress in males, attributed to testosterone's regulatory role. While testosterone's influence on thyroid function is less defined, it is thought to decrease TBG levels, thereby potentially increasing the availability of free thyroid hormones.

Assessing Hormonal Imbalance

Advanced tools for identifying hormone imbalances utilize detailed testing methods, including saliva, serum, and urine analyses. These techniques are designed to provide a thorough understanding of cortisol rhythms, thyroid hormone levels, and the balance of sex hormones. 

Salivary assays, which are less invasive, reflect the levels of free, active hormones, offering insights into the body's functional hormone status. Serum tests measure total hormone levels but can be complex due to the interaction with proteins in the blood, which may affect the interpretation of results. Urine analysis provides a comprehensive view of hormone excretion over time, indicating overall hormone production.

Saliva Tests

Saliva tests are valued for their non-invasive nature and the ability to measure free, bioavailable hormone levels, including major estrogens, progesterone, androgens, cortisol, and melatonin. They offer advantages in cost, convenience, and the accuracy of specific hormones’ measurements. 

However, studies show their reliability may vary with hormone replacement therapy or supplemental hormones, as salivary concentrations can significantly differ from serum levels in these contexts. Therefore,  always consider the method of drug delivery when interpreting results.


  • Non-invasive
  • Cost-effective
  • Convenient for repeated sampling


  • May not accurately reflect serum concentrations, especially with HRT

Example Tests: 

Serum Tests

Serum tests are essential for accurately measuring a wide array of hormones in the blood, providing a detailed overview of an individual's hormonal status. They are particularly valuable for diagnosing various endocrine disorders and evaluating the effectiveness of hormone therapies. While most studies confirm a correlation between saliva and serum cortisol levels, it's important to note that the concentration of cortisol in saliva is consistently lower than in serum. 

Despite this, early morning saliva cortisol measurements can closely reflect serum cortisol levels, offering a less invasive alternative for initial assessments. However, serum tests remain superior for comprehensive evaluations due to their ability to measure a broader range of hormones and provide absolute concentration levels that are critical for diagnosing and managing endocrine conditions.


  • Provides detailed hormonal status
  • Accurate measurement of a broad range of hormones


  • Invasive (requires blood draw)
  • Higher cost and less convenience 

Example Tests:

Urine Tests

Urine tests offer insights into hormone metabolism and the body's excretion of hormones over time, providing a cumulative measure of hormone production. They are particularly useful for assessing how the body processes hormones, rather than just the levels present at a single point in time.


  • Non-invasive
  • Reflects hormone metabolism and excretion


  • Less immediate than saliva or serum levels
  • Can be influenced by hydration and kidney function

Example Tests:

Interpreting hormone test results requires a holistic approach that considers the patient's symptoms, lifestyle, and overall health. It's important to understand that hormone levels, such as cortisol, can vary between tests based on type and timing. 

This variation means that to get a complete picture of a patient's hormonal health, the results from these tests need to be considered alongside what symptoms the patient is experiencing and how they live their daily life. 

Additionally, hormone levels change throughout the day, which highlights the importance of timing when collecting samples for these tests. A comprehensive evaluation ensures that treatment addresses the patient as a whole, interpreting test outcomes within the confines of their real-world implications.

A Root Cause Approach to Restoring Hormonal Harmony

To address hormonal imbalances at their root, dietary strategies play a role, focusing on thyroid health, adrenal function, and the balance of sex hormones. Incorporating nutrient-dense foods that are rich in vitamins and minerals supports overall endocrine health. 

For thyroid function, foods high in selenium, such as seafood and nuts, are recommended for their role in producing thyroid hormones. 

Adrenal health can benefit from a diet that limits processed foods and sugar, which both reduces inflammation and supports cortisol regulation. Additionally, balancing sex hormones may involve managing phytoestrogen intake through foods like flaxseeds and soy, which can mimic estrogen in the body, helping to maintain hormonal balance in certain individuals.

Beyond nutrition, targeted supplementation offers another layer of support. Selenium supplementation can boost thyroid health, while adaptogenic herbs such as ashwagandha and rhodiola offer adrenal support by enhancing the body's resilience to stress. Vitex, also known as chasteberry, is particularly beneficial for women's health, supporting progesterone balance and addressing symptoms of hormonal imbalance like PMS and irregular menstrual cycles.

Lifestyle modifications, including implementing stress reduction techniques, optimizing sleep patterns, and engaging in regular physical activity, are also essential in fixing the root cause of imbalances.

Integrating Hormonal Health Into Overall Patient Care

To effectively integrate hormonal health into overall patient care, a personalized, multidisciplinary approach is essential. By combining the expertise of endocrinologists, gynecologists, and nutritionists, healthcare providers can develop customized treatment plans that not only address the immediate hormonal imbalances but also the root causes behind them. 

This strategy should leverage comprehensive diagnostics and consider the patient’s unique lifestyle and medical history to ensure interventions are both targeted and holistic. This approach enables healthcare professionals to offer care that directly improves health, ensuring treatments align with functional medicine principles for meaningful patient outcomes.


Key Takeaways

  • The thyroid-adrenal axis is central to regulating metabolism and stress response, emphasizing the need for balanced thyroid and adrenal gland function.
  • Sex hormones like estrogen, progesterone, and testosterone significantly influence both thyroid and adrenal functions, affecting overall hormonal balance.
  • Advanced diagnostic tools, including saliva, serum, and urine analyses, are key to accurately assessing hormonal imbalances.
  • A root-cause approach to hormonal imbalances involves dietary changes, targeted supplementation, and lifestyle modifications tailored to individual patient needs.
  • Integrating hormonal health into patient care requires a personalized, multidisciplinary strategy, combining the expertise of various specialists for comprehensive treatment plans.
The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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