16 Jun 2020
How Thyroid Health Impacts Hormones, Fertility and Periods
16 Jun 2020
The function of your thyroid is one of the greatest determinants of your overall health and wellbeing! Almost every single cell in your body has a thyroid hormone receptor – this means that your thyroid function has wide-reaching impacts on practically every aspect of your health.
What is your thyroid?
The thyroid is a butterfly-shaped gland located at the front of your throat. It produces the thyroid hormones triiodothyronine (T3) and thyroxine (T4). Thyroid hormones drive energy production and metabolism in the body, and stimulate the burning of calories. Think of thyroid hormones as an on/off switch for every cell in your body and you will begin to understand why thyroid health is so important!
The most common type of thyroid disorder is called hypothyroidism (or underactive thyroid), which occurs when the thyroid does not make enough thyroid hormone. 90% of hypothyroidism is caused by an autoimmune condition known as Hashimoto’s, which disproportionately affects women. In fact, Hashimoto’s affects 7x as many women as men!
A less common form of thyroid disease is called hyperthyroidism (or overactive thyroid), which occurs when the thyroid produces too much hormone.
Both an underactive and overactive thyroid can impact hormones, fertility and period health, however hypothyroidism is much more likely and common.
Diagnosis of Thyroid Disease
The standard test for diagnosing thyroid disease is thyroid-stimulating hormone (TSH). However, there is some controversy regarding the normal range for TSH. This is especially relevant for infertility, as the TSH level required for optimal fertility is lower than what is recommended for the average adult. Furthermore, TSH alone rarely provides us with enough information about thyroid function. That is why it is extremely important to run a full thyroid panel when assessing for thyroid disease (TSH, Free T3, Free T4 and thyroid antibodies). See this article by Dr. Alaina Gair ND for more information about thyroid testing and diagnosis!
How Thyroid Health Impacts Your Hormones and Period
An underactive thyroid influences your hormonal and reproductive health in the following ways:
- Impairs healthy estrogen metabolism, leading to high estrogen levels.
- Stimulates prolactin, leading to suppressed ovulation.
- Reduces cellular energy available to the ovaries, leading to poor/suppressed ovulation and low progesterone.
- Worsens insulin resistance, increasing your risk of developing Polycystic Ovarian Syndrome (PCOS).
- Decreases coagulation factors, leading to heavy bleeding and periods.
The hormonal changes mentioned above can cause the following symptoms:
- Heavy periods
- Irregular periods
- Skipping periods
- Painful periods
- Breast tenderness
- Skin tags
- Excessive body and facial hair growth
- Thinning hair (on the head)
- Hair loss (from the head)
- Painful or uncomfortable intercourse
- Apathy and low mood
- Brain fog
- Low sex drive
- Fluid retention
- Weight gain
- Cravings for sweets
- Feeling “hangry”
- Feeling cold
How Thyroid Health Impacts Fertility
As we have seen above, an underactive thyroid can alter hormone levels and suppress ovulation, which makes it much more difficult to become pregnant (remember that ovulation is necessary for fertilization and pregnancy to occur). Hypothyroidism’s influence on the menstrual cycle can also interfere with fertility by causing irregular cycles and increasing the likelihood of developing fibroids, endometriosis and PCOS (all these conditions can contribute to infertility).
As we briefly discussed above, a healthy TSH level is essential for optimal fertility outcomes. The research into this topic is so conclusive that fertility clinics regularly use adjusted normal ranges for TSH when assessing their infertility patients.
Autoimmune thyroid disease, or Hashimoto’s, has been associated with increased miscarriage rates and an increased diagnosis of “unexplained infertility”. Hashimoto’s is characterized by elevated thyroid antibodies on testing, again emphasizing how important it is to have a full thyroid panel tested instead of relying on TSH alone.
Finally, recent research into the area of thyroid health and fertility has uncovered the important role that thyroid hormones play in determining egg quality. In this study, exposure to thyroid hormones resulted in significantly improved egg quality – this is especially relevant for fertility patients undergoing assisted procedures such as IVF.
Orouji Jokar T, Fourman LT, Lee H, Mentzinger K, Fazeli PK. Higher TSH Levels Within the Normal Range Are Associated With Unexplained Infertility. J Clin Endocrinol Metab. 2018;103(2):632‐639. doi:10.1210/jc.2017-02120
Toulis KA, Goulis DG, Venetis CA, et al. Risk of spontaneous miscarriage in euthyroid women with thyroid autoimmunity undergoing IVF: a meta-analysis. Eur J Endocrinol. 2010;162(4):643‐652. doi:10.1530/EJE-09-0850
Deroux, A., Dumestre-Perard, C., Dunand-Faure, C. et al. Female Infertility and Serum Auto-antibodies: a Systematic Review. Clinic Rev Allerg Immunol 53, 78–86 (2017). https://doi.org/10.1007/s12016-016-8586-z
Canipari, R., Mangialardo, C., Di Paolo, V. et al. Thyroid hormones act as mitogenic and pro survival factors in rat ovarian follicles. J Endocrinol Invest 42, 271–282 (2019). https://doi.org/10.1007/s40618-018-0912-2
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