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The Estrogen-Thyroid Connection and Its Impact on Women’s Health

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The Estrogen-Thyroid Connection and Its Impact on Women’s Health

Women are disproportionately affected by thyroid dysfunction. According to the American Thyroid Association, women are 5-8 times more likely than men to have thyroid problems. Evidence suggests that estrogen may play a role in this disparity. 

Understanding and addressing the interplay between estrogen levels and thyroid function may be key to optimizing women's health. This article will explore the estrogen-thyroid connection from a root-cause medicine perspective, discussing holistic strategies for addressing hormonal imbalances that impact women's health.


What is The Thyroid, and What Does it Do?

The thyroid gland produces the hormones thyroxine (T4) and triiodothyronine (T3). These hormones are released into the bloodstream and transported throughout the body, bound to a carrier protein called thyroxine-binding globulin (TBG). Upon reaching target tissues, T3 and T4 bind to receptors, influencing metabolism, growth, and development. (19)

How Does Estrogen Affect Thyroid Function?

Estrogen, a hormone predominantly associated with female reproductive function, can influence thyroid function in several ways. Estrogen increases the synthesis of TBG, which binds thyroid hormone and decreases the amount of free thyroid hormone available to the body, triggering symptoms of an underactive thyroid (hypothyroidism). 

A study published in Molecular and Cellular Endocrinology found that prolonged exposure to an estrogen metabolite called 2-methoxyestradiol (2-ME) can induce thyroid cell death and increased production of an autoantibody (anti-thyroid peroxidase) implicated in thyroid autoimmunity.

Another example of the estrogen-thyroid connection can be seen in individuals with polycystic ovary syndrome (PCOS), a common hormonal problem that occurs in women of reproductive age. High estrogen is responsible for many of the hormonal symptoms of this condition, and interestingly, there is a high prevalence of subclinical hypothyroidism (SCH) and Hashimoto's thyroiditis among women with PCOS.

Does The Thyroid Also Have An Influence on Estrogen?

This connection is not unidirectional. Hypothyroidism can exacerbate estrogen dominance. Estrogen is broken down by the liver (called biotransformation) so that it can be eliminated from the body. Hypothyroidism slows the liver's detoxification pathways, resulting in a buildup of estrogen.

The Symptoms of Imbalances in the Estrogen-Thyroid Connection

Imbalances in the estrogen-thyroid connection can manifest in various symptoms and conditions due to the intricate interplay between these hormonal systems. 

Signs & Symptoms of Hypothyroidism:

  • Fatigue
  • Unintentional weight gain
  • Constipation
  • Cold intolerance
  • Depression
  • Muscle and joint pain
  • Changes to menstrual cycles
  • Dry skin
  • Brittle nails
  • Hair loss
  • Thinning of the outer third of the eyebrow
  • High cholesterol (46

Signs & Symptoms of Estrogen Imbalance:

  • Menstrual irregularities
  • Unexplained weight gain or difficulty losing weight
  • Mood disturbances
  • Brain fog, difficulty concentrating, and memory problems
  • Headaches
  • Hot flashes
  • Acne (45

Estrogen dominance has been associated with the development of conditions like uterine fibroids, ovarian cysts, and endometriosis, which can cause pelvic pain, heavy menstrual bleeding, and fertility issues.

The Root Causes of Imbalances in the Estrogen-Thyroid Connection

Understanding the potential root causes of estrogen imbalance and thyroid dysfunction helps to unravel the estrogen-thyroid connection and construct effective treatment protocols.

Nutrient Imbalances

Estrogen biotransformation involves a series of reactions that occur in the liver. Nutrients, including B vitamins, magnesium, indole-3-carbinol (I3C), and sulforaphane, act as cofactors for the enzymes that fuel these pathways. Insufficient levels of these nutrients slow the elimination of excess estrogen. (37

Similarly, the thyroid requires a wide array of nutrients to produce and convert thyroid hormones properly. Deficiencies in iodine, iron, tyrosine, zinc, selenium, magnesium, and vitamins Bs, C, D, and E have been implicated in thyroid dysfunction. (46

Environmental Toxins

Endocrine-disrupting chemicals (EDCs) interfere with hormone production, metabolism, and signaling pathways. These toxins can enter the body through various sources, including contaminated food, water, air, and consumer products. 

Xenoestrogens are a subcategory of EDCs; they mimic estrogen or interfere with estrogen receptors, contributing to an estrogen-dominant state. 

Certain EDCs can inhibit the uptake of iodine by the thyroid gland, leading to decreased thyroid hormone synthesis. Others may interfere with the activity of thyroid receptors or disrupt the conversion of T4 to T3. (25, 46


Chronic stress can dysregulate the hypothalamic-pituitary-adrenal (HPA) axis, increasing cortisol production. Elevated cortisol levels can disrupt the feedback mechanisms that regulate the production of TSH and gonadotropin-releasing hormone (GnRH), ultimately affecting thyroid and estrogen pathways. (17)

How Lab Testing Can Assess This Connection

Labs are required to diagnose hormonal imbalances definitively.

Thyroid Hormones

While it is standard practice to screen for thyroid dysfunction by measuring thyroid-stimulating hormone (TSH), ordering this single test can miss up to 7% of cases of hypothyroidism. 

A comprehensive thyroid panel, which typically includes TSH, total T3/T4, free T3/4, and thyroid antibodies at minimum, more accurately assesses thyroid health and hormone production and conversion. 

The following panels can help you comprehensively assess the thyroid cascade:

Estrogen Levels

Blood panels are an excellent place to start for assessing circulating levels of estrogen because they are typically covered by insurance. Measuring estrogen levels on day three of the menstrual cycle is generally recommended. In some cases, comparing estrogen and progesterone levels on days 19-22 of the menstrual cycle can be beneficial. (5

Here are some examples of hormone blood tests: 

Because estrogen levels fluctuate throughout the month, a single blood test may not be able to detect estrogen imbalance. Urine and saliva tests are available to measure estrogen levels throughout a menstrual cycle and assess how estrogen is made and metabolized in the body. These labs may be able to more accurately detect subtle imbalances in estrogen, as well as provide insight into why the imbalance is occurring: 


How to Treat Estrogen Imbalances and Thyroid Health

The patient's history, symptoms, and lab results will guide personalized treatment plans to alleviate symptoms and correct the root causes of hormonal imbalances. 

First, directly address hormonal imbalances

Correcting hormonal imbalances with bioidentical hormones or botanical medicine as a first step acts as a band-aid to provide quick symptom relief. While these do not address the underlying root causes, they allow patients to feel better, which can motivate them to make the more challenging changes required to correct underlying causes.

Thyroid replacement therapy is standard therapy to rebalance thyroid hormones in cases of hypothyroidism. Synthetic and naturally porcine-derived medications deliver T4 and/or T3 hormones into the system to bring TSH, T4, and T3 into their normal reference ranges and relieve associated hypothyroid symptoms. 

Bioidentical hormone therapy is also a potential treatment for balancing sex hormones. Because estrogen dominance is most commonly associated with thyroid dysfunction, it can be beneficial to administer continuous or pulsed progesterone during the menstrual cycle.

Herbal supplements can effectively normalize hormone levels in subclinical or mild hormone imbalances. Chasteberry acts at the pituitary level to balance estrogen and progesterone levels and normalize menstrual irregularities. Ashwagandha root extract in doses of 300 mg twice daily is indicated for treating SCH. 

Second, focus on addressing the root causes

While it often takes more time to observe the resolution of symptoms, reestablishing homeostasis by addressing the root causes of hormonal imbalances increases the likelihood of long-term success and reduces reliance on quick-fix treatments.

Address Diet/Add Nutrients

This is important because nutrients provided through diet or supplements are essential for hormone synthesis, metabolism, and balance. 

Nutrients To Add: 

Cruciferous vegetables such as broccoli, cauliflower, kale, and Brussels sprouts are rich sources of I3C and sulforaphane, which support the liver's estrogen detoxification pathways. While cruciferous vegetables benefit estrogen metabolism, there has been debate regarding their impact on thyroid function due to their goitrogenic compounds, which can interfere with iodine uptake and potentially disrupt thyroid hormone synthesis. However, research suggests that the goitrogenic effects of cruciferous vegetables are minimal when consumed in moderation and in the context of a well-balanced diet.

Research shows that the following vitamins and minerals have dual actions in supporting healthy estrogen levels and thyroid function: 

  • Iodine:150 mcg once daily; dietary sources include iodized salt, seaweed, seafood, and dairy. 
  • Selenium: 200 mcg once daily; food sources include Brazil nuts and seafood.
  • Vitamin D: 2,000-5,000 IU once daily; in addition to sunlight exposure, vitamin D can be obtained naturally by eating fatty fish and fortified milk.

Incorporate Stress Management Techniques

Chronic stress can cause estrogen and thyroid imbalances through its ability to dysregulate the HPA axis. Incorporating stress management practices into daily routines can mitigate the detrimental effects of stress on hormonal health. 

How You Do This:

30% of adults say they feel less stressed after exercising. Exercise regulates the release of stress hormones, such as cortisol, and promotes the release of natural mood-lifting chemicals. Additionally, exercise supports healthy estrogen metabolism and reduces body fat, an estrogen reservoir. 

Adaptogenic herbs are a class of botanicals that help the body adapt to stressors by modulating the HPA axis and the sympathetic nervous system. Examples of adaptogenic herbs include:

  • Ashwagandha: 300-600 mg of standardized extract per day
  • Rhodiola: 100-600 mg of standardized extract per day

Mind-body practices integrate the mind and body through mindfulness, meditation, breathing exercises, movement, and relaxation techniques. They activate the parasympathetic nervous system, which is associated with "rest and digest" physiological functions and relaxation. Examples of mind-body practices include acupuncture, meditation, biofeedback, and deep breathing.

Reduce Environmental Toxins

EDCs and other environmental toxins can interfere with hormone function and metabolism. They mimic, block, or alter hormone signaling pathways, disrupting estrogen, thyroid, and other hormonal systems. 

How You Do This:

1. Reduce Exposure

  • Choose organic produce to minimize exposure to pesticides and herbicides commonly found in conventionally grown fruits and vegetables. Refer to the Dirty Dozen list to prioritize purchasing organic versions of the most contaminated produce items and the Clean 15 list to guide purchases of conventionally grown produce with lower pesticide residues.
  • Use non-toxic household cleaning products and cosmetics made from natural ingredients to avoid exposure to harmful chemicals like phthalates, parabens, and synthetic fragrances. The Environmental Working Group's Skin Deep website is a valuable resource for researching ingredient safety and product ratings.
  • Reduce the use of plastics by opting for glass or stainless steel containers for food storage and avoiding single-use plastics such as water bottles, straws, and utensils.
  • Filter drinking water to remove contaminants that may be present in tap water.
  • Increase ventilation in indoor spaces to reduce exposure to indoor air pollutants.

2. Enhance Detoxification

  • Stay hydrated by drinking plenty of water throughout the day to support kidney function and facilitate the elimination of toxins through urine.
  • Consume a diet rich in fiber from fruits, vegetables, whole grains, and legumes to promote regular bowel movements and enhance toxin excretion through the digestive system.
  • Incorporate cruciferous and allium vegetables into meals to support liver detoxification pathways.
  • Incorporate sauna sessions into your routine to mobilize toxins and eliminate them from the body through sweat.


Key Takeaways

  • By implementing a holistic treatment plan that addresses estrogen and thyroid imbalances, women can achieve hormonal harmony and improve overall health outcomes.
  • A treatment plan that addresses the estrogen-thyroid connection encompasses lifestyle modifications, dietary adjustments, supplementation, stress management techniques, and natural detoxification strategies.
  • Healthcare professionals should consider this connection when developing personalized treatment plans to optimize women's hormonal health.
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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