How Estrogen and Progesterone Impact Your Thyroid Hormones

Estrogen and Thyroid Hormones

Research shows that estrogen can increase thyroid cell growth and thyroglobulin. Thyroglobulin is a considered a precursor to thyroid hormones. When it is time to make thyroid hormones, your thyroid will take iodine from the blood and attach it to thyroglobulin in order to make thyroid hormones. So a little bit of estrogen is necessary for thyroid hormone function.

But if you have too much estrogen (estrogen excess), this can lead to an enlarged thyroid called goiter.

Estrogen also increased thyroxine-binding globulin (TBG). This a protein make by the liver that shuttles thyroid hormone in the blood. High TBG leads to low free thyroid hormones. Free T3 is what can enter cells and instruct the cell about metabolism, growth, and all the other functions of thyroid hormones.

So high TBG may cause a functional deficiency in thyroid hormone leading to symptoms of hypothyroidism.

Progesterone and Thyroid Hormones

Progesterone and thyroid hormones have a reciprocal relationship. You need adequate amounts of thyroid hormone for your ovaries to make progesterone but progesterone also helps the thyroid. For example, research shows that progesterone can increase thyroid hormone levels in the blood. Progesterone also decreases TBG so that more thyroid hormone can be free and interact with your cells.


  • Estrogen excess can inhibit proper functioning of thyroid hormones.

  • Progesterone deficiency can hinder the production and functioning of thyroid hormones.

Since estrogen excess and progesterone deficiency are hormonal imbalances that often occur together, your sex hormones can significantly impact your thyroid hormones. So if you are struggling with hypothyroidism and still have symptoms on medication, be sure to investigate your sex hormones. Learn how to test your sex hormones here.






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I'm Dr. Carly and my mission is to create a health revolution. I believe that another prescription is not the answer. I believe in using natural therapies that go beyond the symptoms. And I believe that doctors should spend way more than 7 minutes with a patient.