The Thyroid-Hormone Feedback Loop: Can Hashimoto’s Cause Low Estrogen?

You know estrogen plays a powerful role in your body as one of the fundamental building blocks of health and body regulation. But did you know that when this key hormone is out of balance, it doesn’t just affect reproductive health; it can disrupt multiple systems, including the thyroid?

If you’ve ever wondered whether low estrogen might be linked to Hashimoto’s, you’re not alone. Understanding the connection between estrogen and your thyroid health could help you uncover why your symptoms persist and support your health more effectively.



In this article, we’ll break down how estrogen influences thyroid function, how Hashimoto's may impact estrogen levels, and natural strategies that can help you restore balance and alleviate symptoms.

Table of Contents

Yes, Hashimoto’s disease can potentially affect estrogen.

It is a recently known fact that estrogen also has a direct effect on the thyroid economy. This means that it can influence the production and regulation of thyroid hormones and enzymes, including:

• Triiodothyronine (T3) 
• Thyroxine (T4)
• Thyrotropin-releasing hormone (TRH)
• Thyroid-stimulating hormone (TSH)
• Thyroid peroxidase antibodies (TPOAb)

Hashimoto’s affects more than just your thyroid. It impacts your entire life. 

From navigating the disease to managing symptoms, your Hashimoto’s may cause a host of issues and potentially put you at risk for further developing other autoimmune disorders. 

Don’t succumb to living with your Hashimoto’s symptoms. Fight back with the power of something you do every day: eating! 



HealthierU and Dr. Donna Sergi are here to tell you that you don’t have to submit to your Hashimoto’s disease. Along with developing a nutritional treatment plan, we will coach you on making food choices that may reduce your Hashimoto’s symptoms and help you on a path toward better health and wellness.

So far, there isn’t enough research to definitively say whether Hashimoto's causes low estrogen or not. However, a few studies have suggested there may be a connection between the two. 



Thyroid dysfunction has long been associated with menstrual irregularities, but the exact link between thyroid disorders and low estrogen levels has yet to be found. 

hypothyroidism because the immune system launches a constant attack on the thyroid, slowly damaging it and affecting its ability to create and regulate thyroid hormones over time. 

Too much estrogen may stoke autoimmune responses, which may be why pregnancy can trigger thyroid dysfunction.



Estrogen suppresses thyroid hormones and increases the production of thyroid-stimulating hormones (TSH), whereas progesterone increases thyroid hormones. High estrogen and low progesterone levels may create a combination that impairs the thyroid's function properly. 

However, present research suggests that high levels of estrogen may be linked to thyroid disorders, like hypothyroidism and Hashimoto’s.

• A study was completed to explore the link between patients with polycystic ovarian syndrome (PCOS) and the prevalence of Hashimoto’s thyroiditis. It found that an increased estrogen and estrogen/progesterone ratio directly correlated with high anti-TPO levels in PCOS patients.
• This study suggests that high estrogen exposure in pregnant women may even significantly lead to thyroid disorders in offspring. 
  

Estrogen dominance, also referred to as unopposed estrogen, is a theory first proposed in 1996 by John R. Lee and Virginia Hopkins in their book What Your Doctor May Not Tell You About Menopause: The Breakthrough Book on Natural Progesterone.

It’s used as an umbrella term to describe any condition where estrogen levels are high or normal, and progesterone levels are low. It doesn’t always mean that estrogen itself is high — sometimes estrogen can be normal, but progesterone is too low, making estrogen the “dominant” hormone in the relationship.

Think of it like a seesaw: even if one side doesn’t go up, the other can drop, and the balance still shifts.

This hormonal imbalance is often connected to:

• Stress
• Poor detoxification
• Perimenopause
• Certain medications
• Thyroid issues

When estrogen is the dominant hormone, it can contribute to thyroid dysfunction, inflammation, and autoimmune flare-ups — which is why it’s commonly discussed in relation to Hashimoto’s.

 

At HealthierU, we’ve seen firsthand how estrogen imbalance can appear alongside thyroid concerns. Instead of treating symptoms separately, our approach focuses on understanding how hormones work in tandem, because a thyroid flare-up may actually begin with a hormonal imbalance elsewhere in the body.

Estrogen and progesterone work together, along with the adrenal and thyroid hormones, to maintain homeostasis and biological function.

There are four types of naturally occurring estrogen, which are:

1. Estrone (E1)
2. Estradiol (E2)
3. Estriol (E3)
4. Estetrol (E4)

Estrogen controls various functions, but it is primarily responsible for regulating the growth, development, and physiology of the human reproductive system. It also influences the endocrine, cardiovascular, skeletal, and connective tissue systems. 

The primary function of progesterone is to prepare the female body for pregnancy; this means increasing endometrial tissue to encourage egg implantation. 

Frank estrogen dominance happens when estrogen levels are too high and cause an uneven balance of progestin-to-estrogen ratios. 

High estrogen levels combined with normal progesterone levels are the most common type of estrogen dominance and usually occur when:



• The body is making too much estrogen
• Excess estrogen is coming from an external source
• The body is having difficulty removing excess estrogen
  

The second type is known as relative estrogen dominance. It occurs when estrogen levels are normal, but progesterone is exceptionally low, leading to an imbalance in the progesterone-to-estrogen ratio.

This situation is more common after pregnancy or in menopause and is due to the rapid decrease in progesterone production. 

Other causes of low progesterone may include:

• Anovulation (no ovulation)
• Polycystic ovarian syndrome (PCOS)
• Hyperprolactinemia (elevated prolactin)
• Low cholesterol
• Increased cortisol levels

Symptoms of estrogen dominance may include:

• Weight gain 
• Heavy or light periods
• Severe premenstrual syndrome (PMS) symptoms
• Fatigue
• Fibroids in the uterus
• Fibrocystic breast lumps
• Low sex drive
• Low mood or anxiety

Other symptoms may include:



• Bloating
• Headaches
• Disrupted sleep
• Hair loss
  

Your health is influenced by many different factors, and your entire body is shaped by everything from genetics to lifestyle choices like diet and nutrition. While medication and therapies are often essential, nutrition also plays a meaningful role in easing symptoms and supporting thyroid health. 

HealthierU invites you to learn more about the efficacy of nutrition and the role diet may have in helping you manage your Hashimoto’s symptoms, in conjunction with following the guidance of your primary care provider and other trusted medical professionals when treating Hashimoto’s and thyroid-related conditions. 

Hormonal birth control is designed to stop ovulation by suppressing the body’s natural production of estrogen and progesterone. 

By introducing artificial reproductive hormones into the body, natural hormone production temporarily halts, which may possibly lead to hormonal imbalances such as estrogen dominance. 

There are two forms of hormonal birth control:

1. Estrogen and progestin (artificial progesterone)
2. Progestin-only



Progesterone is primarily responsible for preventing pregnancy, whereas estrogen only controls menstrual bleeding. Both estrogen and progestin birth control and progestin-only birth control will cause estrogen to lower. 

While there is no direct evidence that hormonal birth control causes thyroid disease, a 2021 cross-sectional study suggests that there may be a strong association between hypothyroidism and long-term hormonal birth control use (more than ten years). 

Xenoestrogens are foreign estrogen-mimicking compounds that may be synthetic or natural. 

Exposure to these compounds may cause increased estrogen levels as they bond to estrogen receptors and induce responses typical to estrogen. 



Various products contain xenoestrogens, but exposure can occur through non-organic foods, plastics, the water supply, and personal care products. 

A few products that contain xenoestrogens include:

• Plasticizers
• Perfume fixatives, like parabens and phthalates
• Soy
• Solvents
• Industrial chemicals and pollutants, such as insecticides 
• Epoxy resins 
• Polycarbonate 
• Other plastics 
• Herbicides
  

Estrogen replacement therapy involving synthetic hormones is often prescribed for perimenopause and menopausal patients to ease uncomfortable symptoms. 

As the body moves through perimenopause and into menopause, estrogen levels shift before they naturally decline. If someone is using hormone therapy while their body is still making estrogen, it may cause estrogen levels to become too high. 

According to research, excess body fat has been associated with increased levels of estrogen, particularly in post-menopausal women. 

Many factors are linked to obesity, like inflammation and changes in the proteins that control appetite and metabolism, which can also lead to estrogen upregulation. 

By supporting your body with a quality diet and nutrition, you may help prevent excess estrogen from fat cells and lower your risk of developing Hashimoto’s.

HealthierU prioritizes health over societal expectations regarding body image. We understand how toxic diet culture and cultural stigmas can affect our clients. Our goal is to help you use nutrition to make steps toward a happier, healthier you.

 

Dr. Donna Sergi will help you achieve your nutritional health goals with a natural treatment for hypothyroidism founded on compassion, understanding, and zero judgment.

Certain genetic sequences may impact how well your body metabolizes, regulates, and produces estrogen. 

For example, one gene expression, referred to as COMT, uses DNA to instruct estrogen to be produced through a protective pathway. 

The COMT gene allows us to break down catecholamines, which are hormones made by your adrenal gland, and catechol-estrogens, specifically through methylation. 

The COMT gene helps your body clear out catecholamines (hormones made by the adrenal glands) and catechol-estrogens through methylation, allowing your body to break down adrenal hormones and certain estrogen types.

Methylation is a biochemical process where a small molecule called a methyl group replaces a hydrogen atom in DNA, proteins, hormones, or other molecules. This process is responsible for turning off processes that create proteins, steroids, and hormones (such as estrogen).



So, if you have an alteration in your COMT gene, it may slow the conversion of hydroxy-estrogen to methoxy-estrogen. Consequently, there may be a build-up of hydroxy-estrogens and estrogens in the body. 

Now that we’ve answered questions like “Can Hashimoto’s cause low estrogen?” and “How does Hashimoto’s affect estrogen?” let’s talk about how you can get a handle on your excess estrogen and Hashimoto’s with diet and nutrition. 

For some, it can be difficult to navigate food choices when you’re suffering from the effects of a thyroid dysfunction disorder. It can be even more challenging if you feel like you’re making all the right food choices, but nothing is working.

Dr. Donna Sergi understands how frustrating this feeling can be and is here to help you find a solution that works for you. 



Schedule your first appointment to begin your nutritional journey toward a healthier you.