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PCOS and Hashimoto's Disease: What's The Connection?

Explore the connection between polycystic ovary syndrome and Hashimoto's thyroid disease in this article.
PCOS and Hashimoto's Disease: What's The Connection?
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Polycystic ovary syndrome and Hashimoto's thyroiditis are common disorders that often go undiagnosed for a long time. These two conditions share many similarities, and we want to know: are they connected?

What is Hashimoto's thyroiditis?

Hashimoto's disease is an autoimmune condition in which the immune system mistakenly attacks the thyroid gland, the small, butterfly-shaped gland at the base of the neck. The thyroid gland is responsible for producing thyroid hormones that regulate your body's energy use, along with many other essential functions.

As part of the endocrine system, the thyroid gland makes and stores hormones that help regulate the body's metabolism in the form of blood pressure, blood temperature, and heart rate.

With Hashimoto's disease, antibodies directed against the thyroid gland lead to chronic inflammation. Research is inconclusive about why some people make these antibodies. Studies point to nutritional deficiencies, damage to the pituitary gland, certain medications, pregnancy, significant hormonal events, or, most probably, family history. It is the most common cause of hypothyroidism in the United States, affecting roughly 5% of the population. What's more, is autoimmune thyroid disorders affect 5%–20% of the female population of fertile age.


Common symptoms of Hashimoto's disease include:

  • Extreme fatigue
  • Weight gain or difficulty with weight loss
  • Cold intolerance
  • Joint stiffness or muscle pain
  • Constipation
  • Depression
  • Puffy eyes or face.
  • Dry skin
  • Hair loss
  • Heavy or irregular periods
  • Infertility or difficulty becoming pregnant
  • Difficulty thinking or concentrating
  • Slow heartbeat

What is polycystic ovary syndrome (PCOS)?


Polycystic ovary syndrome, also known as PCOS, is a common health problem. It affects 6–12% of reproductive-aged women and is one of the most common causes of infertility. Although the exact cause of PCOS is unknown, experts agree that PCOS is related to many different factors working together. These factors include insulin resistance, increased hormones called androgens, and an irregular menstrual cycle.


PCOS is often misinterpreted as a disease, but in fact, it is a set of symptoms that may present together. Typically, women with this syndrome have irregular or absent menstrual periods, higher than average androgen levels (androgens are male hormones), insulin resistance, and impaired glucose metabolism. The latter occurs when the ovaries develop small collections of follicles/cysts and fail to release eggs regularly.


Common symptoms of PCOS include:

  • Missed, irregular, or very light periods
  • Large ovaries or ovaries that have many cysts
  • Excess body hair, including the chest, stomach, and back 
  • Weight gain, especially around the belly
  • Acne or oily skin
  • Infertility 
  • Skin tags
  • Dark or thick skin patches on the back of the neck, armpits, or under the breasts


What is the connection between PCOS and Hashimoto's?


While the link between autoimmune thyroiditis and polycystic ovary syndrome has been a table topic in the medical community, its pathogenesis isn't totally understood. 


Research shows that women with PCOS are three times more likely to have Hashimoto's thyroiditis than women without this hormonal syndrome. While the exact cause of both diseases is unclear, researchers suspect that genetic factors and environment play a role in the onset of both disorders.  


2013 study from the Shanghai Key Laboratory of Female Reproductive Endocrine-Related Diseases suggests that PCOS may be a kind of autoimmune disease and has a close association with autoimmune thyroiditis. This suggestion is due to the high rate of TSH (thyroid-stimulating hormone) and TPO antibodies found in PCOS patients compared to control groups. You can get your metabolism evaluated with the Allara Diagnostic Test


Those with an autoimmune disease are more likely to develop other autoimmune disorders (called polyautoimmunity). Drawing from the conclusion in the Shanghai study, someone with Hashimoto's thyroiditis may be at higher risk of developing polycystic ovary syndrome if it is, in fact, a kind of autoimmune disease. In fact, it appears that if you have PCOS, you may be at a 3x higher risk of developing Hashimoto's disease than women without PCOS. 


Given this knowledge, it is advantageous for women diagnosed with PCOS to routinely check their thyroid function to determine their need for further evaluation with a thyroid specialist. Knowing your numbers is essential to educate yourself and communicate confidently with a physician you trust. 

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Testing TSH (thyroid-stimulating hormone) alone does not give you a comprehensive understanding of your thyroid function. TSH measures how much T4 the thyroid is being asked to make. Other helpful thyroid tests include:

  • T4 and T3 to determine the amount of thyroid hormones your thyroid produces
  • TPO antibodies to detect autoimmune thyroid conditions
  • Reverse T3 to determine how your body converts T4 to T3 

Managing your health when diagnosed with both PCOS and hypothyroidism


Patients with PCOS and Hashimoto's disease see worse metabolic, cardiovascular, and reproductive outcomes. For this reason, it's important that patients who are concerned about their fertility be screened for autoimmune thyroid disease and polycystic ovary syndrome because of their known impact on sex hormones and fertility. Then, we recommend you work closely with your healthcare to determine the ideal treatment for your particular needs.


Allara Health's Lead Dietitian, Felice Ramallo, also explains that lifestyle changes and nutrition could help minimize the symptoms of both PCOS and hypothyroidism. 


Support a healthy, robust metabolism

Since both conditions can decrease metabolism, it may be helpful to find ways—both nutritionally and through lifestyle choices—that you can support a healthy, robust metabolism. 


We suggest you consider the following three best practices: 

  • Engage in physical activity and strength training 
  • Eat frequently and healthfully throughout the day, aiming for between 4 and 6 meals and snacks 
  • Listen to hunger and fullness cues to eat enough food


Eat an anti-inflammatory diet

Since PCOS and hypothyroidism are both inflammatory conditions, it may be beneficial to incorporate anti-inflammatory foods. Excellent anti-inflammatory foods include avocados, leafy greens, berries, salmon, sardines, chia seeds, flax seeds, and walnuts into your meals. 


When in doubt, you can't go wrong opting for colorful vegetables, fruits, fatty fish, nuts, and seeds. These foods are all packed with vitamins and nutrients that support your body, avoid sugar 'spikes' and 'crashes,' and help prevent bouts of inflammation. In the case of our favorite vegetables and fruits (such as blueberries, apples, and leafy greens), they contain natural antioxidants and polyphenols, which are protective compounds found in plants. 


Practice intentional eating

Intentional eating can also be an excellent way to ensure you get the specific nutrients your body may be lacking if you have PCOS or hypothyroidism. Try to incorporate foods that have the following in them:



Iodine is key to supporting a healthy thyroid! Opt for iodized salt, eggs, and sea vegetables (like seaweed) when possible. 


Zinc is especially important for hormone production and regulation. Excellent sources of zinc include oysters, lentils, pumpkin seeds, chickpeas, cashews, and oatmeal. 


Selenium is also crucial in regulating hormones. Go-to sources of this nutrient include Brazil nuts, sardines, eggs, and beans. 


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