How Does Estrogen Dominance Lead To Hypothyroidism?

Women suffer from hypothyroid disease at a rate of approximately ten times that of men. Although the underlying causes of this huge shift are unclear, the link between thyroid and estrogen is one of the key factors. Some doctors suggest estrogen dominance - after autoimmune diseases - is the primary cause of many hypothyroid cases. Studies have also confirmed that the imbalance in the blood levels of estrogen and progesterone directly affects thyroid function. 

What Is Estrogen Dominance?

Estrogen is often referred to as a "female hormone," as it plays an essential role in the control and regulation of the female body - from menstrual cycle and fertility to memory and skin. The estrogen levels in the blood fluctuate over time and begin to decrease during peri-menopause (around 50 to 55 years of age) and are eventually become static once menopause hits.

"Estrogen dominance" is a term used to describe the health condition when your body has much estrogen in your system - compared to progesterone. However, this doesn't necessarily mean the estrogen levels in the blood are too high. It could mean that there is an imbalance of the estrogen and progesterone or that your progesterone levels are too low. Both female hormones regulate and control the production of one another. Therefore, if your body has low progesterone levels, you will be estrogen dominant. Estrogen dominance can also occur if your estrogen levels are normal and are not outside the normal limits.

What Is The Role Of Estrogen In Thyroid Regulation?

Of note, progesterone levels are balanced proportionate to estrogen. This means one can have estrogen dominance if progesterone is deficient in the body. This hormonal imbalance has a strong effect on the thyroid gland, and it can be a potential cause of hypothyroidism in those susceptible. In a majority of hypothyroidism, an autoimmune disease called "Hashimoto's thyroiditis" is the primary cause. However, for Hashimoto's development, other factors such as genetic predisposition, a trigger, and intestinal hyperpermeability (leaky gut) must also be in place. 

In the absence of these factors, estrogen/progesterone imbalance is considered the primary cause of hypothyroidism. About 4.7 percent of the U.S. adult population has hypothyroidism, that's almost five out of 100. Following hormone-disrupting causes are thought to be the leading contributing factors;

  • Poor diet -low in fiber, high in meat and dairy

  •   Genetics

  • Obesity

  • Stress

  • Liver and biliary congestion

  • Side effects of certain medications

  • Oral contraceptives and Synthetic hormone replacement therapy (HRT)

  • Pesticides

  •   Xenohormones - a group of human-made laboratory synthesized chemicals present in foods, plastics, personal care items, household products, air pollution, pesticides, etc.

How Does Estrogen Dominance Lead To Hypothyroidism?

Estrogen dominance or imbalanced estrogen/progesterone levels play an essential role in the regulation of the endocrine system - including the thyroid hormone.

This hormonal imbalance stops the conversion of T4 into the T3 hormone, which leads to low levels of T3 in the body. This means that the patient will experience the symptoms of hypothyroidism, although there is not a direct issue with the thyroid gland. Too much estrogen or low levels of progesterone can also block the uptake of T3 (active thyroid hormone), once again leading to the development of hypothyroidism.

Body conditions like peri-menopausal period and other estrogen disturbers (listed above) causes a significant decrease in the progesterone levels and often manifest strong symptoms of hypothyroidism. 

How to Avoid Estrogen Dominance?

You can't change the non-modifiable factors such as age and menopause. However, here's what you can do to avoid estrogen dominance;

  •          Diet - Eat a diet rich in fiber to flush out excess estrogen. Avoid a diet high in meat and dairy

  •          Minimize xenohormones exposure - Avoid hormone disruptors, i.e., plastic water bottles, Styrofoam, cosmetic products, and pesticides

  •          Avoid chronic stress

  •          Quit smoking

  •          Avoid oral contraceptives and HRT

Ashley Stalmack