The thyroid and your menstrual cycle

Woman thyroid imbalance

Key points:

  • The thyroid plays a main role in regulating your menstrual cycle, as well as your metabolism. 
  • When the thyroid is out of balance it can cause various symptoms such as irregular periods, low energy, weight changes, temperature changes, skin changes and more.
  • Signs of low thyroid function or hypothyroidism include cold extremities, weight gain, exhaustion, depression, constipation, dry skin, heavy periods and irregular periods.
  • Signs and symptoms of an overactive thyroid or hyperthyroidism include insomnia, weight loss, anxiety, hyperactivity, feeling highly irritable, sweating, irregular and absent periods, PMS and infertility. 
  • The thyroid can be affected by diet, nutrient deficiencies, inflammation, stress, the environment, exercise, infection, gut imbalance, viruses, medication use, pregnancy and more. When the thyroid is out of balance it is important to address the root cause.
  • The hypothalamus- pituitary- thyroid axis (HPT axis) is the main communication pathway from the brain to the thyroid and it functions to maintain normal levels of thyroid hormones in the body. 
  • Thyroid imbalance can affect your sex hormones in a number of different ways including creating oestrogen dominance, an inability to clear excess oestrogen, excess prolactin production resulting in lack of ovulation, irregular periods, worsening PMS.
  • In hypothyroidism there is often lower oestrogen and androgen production.
  • In hyperthyroidism there can be an increased conversion of androgens to oestrogen causing signs of hormone imbalance.

Did you know that your thyroid plays not only a major role in regulating your metabolism, but also in the regulation of your sex hormones? Therefore it may be the case that if you are suffering from a hormone imbalance, it may in fact be due to an imbalance of the thyroid.

Let’s start off by understanding what the thyroid gland is and what it does:

The thyroid is an endocrine (hormone) gland that is situated at the front of the neck (when the gland is at its normal size you won’t be able to feel it). This gland’s job is to take in iodine and create the thyroid hormones T3 (triiodothyronine) and T4 (thyroxine) with help from the enzyme thyroid peroxidase.

The thyroid gland is vital for your health because one of its main roles is to regulate the metabolism of the body. The thyroid, therefore, plays an important role in body weight, energy levels, and body temperature, but it also plays a role in regulating your menstrual cycles, maintaining your heart rate, and much more. 

The thyroid hormones are released into the bloodstream based on the needs of the body; for example, during pregnancy, the body needs to provide both the mother and baby with sufficient thyroid hormone therefore more is released. 

In order to keep these hormones in balance, the brain (specifically the hypothalamus and pituitary gland) communicates to the thyroid gland to regulate the release of T4 and T3.

What happens when the thyroid is out of balance?

When the thyroid is out of balance it can cause various symptoms such as irregular periods, low energy, weight changes, temperature changes, skin changes and more. It is important to note that even if the thyroid hormones are within the range of blood tests but are not in the optimal range you may still be suffering from many of these symptoms. 

Let’s explore what happens when the thyroid is both under and overactive.

Hypothyroidism:

Hypothyroidism can be classified as too little thyroid hormone being produced from the thyroid gland. The most common cause of hypothyroidism is Hashimoto’s disease (or Hashimoto’s thyroiditis).

Symptoms of hypothyroidism can vary greatly depending on the levels of thyroid hormone present. Hypothyroidism may physically manifest in many ways and can often be confused for sex hormone imbalance:

  • Cold extremities
  • Weight gain 
  • Exhaustion 
  • Depression and other mood issues
  • Constipation 
  • Dry skin 
  • Heavy periods 
  • Irregular periods

Hyperthyroidism:

Hyperthyroidism on the other hand is when there is too much thyroid hormone being released from the thyroid gland. The most common cause of hyperthyroidism is Graves’ disease.

Some typical symptoms of hyperthyroidism:

  • Insomnia
  • Weight loss
  • Anxiety 
  • Hyperactivity 
  • Highly irritable 
  • Sweating 
  • Irregular and absent periods 
  • PMS 
  • Infertility

Why does the thyroid get out of balance?

The thyroid can be affected by diet, nutrient deficiencies, inflammation, stress, the environment, exercise, infection, gut imbalance, viruses, medication use, pregnancy, and more. When the thyroid is out of balance it is important to address the root cause.

Commonly the thyroid is out of balance due to an interaction of:

Genetic predisposition – influenced by the environment – partnered with a potential leaky gut

Each individual is different and this is why testing and delving into your health history in a consultation is so important to discover what the root cause of imbalance may be for you.

What else may be causing my thyroid imbalance?

It is important to understand if your thyroid imbalance has an autoimmune component (e.g. Hashimoto’s or Graves’ disease), but there are also other reasons why your thyroid may be out of balance including thyroiditis (inflammation of the thyroid gland), hereditary conditions, iodine deficiency, certain medications and surgery.

So how can the thyroid affect your sex hormones?

So often thyroid issues are undiagnosed as they are mistaken as issues with a hormone imbalance. This can actually be the other way around and the true cause of hormone imbalance may be your thyroid. The thyroid communicates with the brain, adrenal glands, and ovaries, therefore any disruption in this pathway can cause hormone imbalance.

A thyroid imbalance can affect your sex hormones in the following ways:

  • Compromises our ability to clear excess oestrogen, leading to oestrogen dominance or unopposed oestrogen
  • Leads to excess prolactin production, resulting in lack of ovulation 
  • Causes irregular periods 
  • Worsens PMS 
  • In hypothyroidism there is often lower oestrogen and androgen production
  • In hyperthyroidism there can be an increased conversion of androgens to oestrogen causing signs of hormone imbalance.

A note about the brain and the thyroid:

One of the main causes of thyroid imbalance (which can subsequently lead to hormone imbalance) is stress. Therefore it is important to mention the communication pathway of the brain to the thyroid – as disruption to this pathway is one of the most common causes of thyroid imbalance. 

This pathway is called the HPT axis – this is the hypothalamus-pituitary-thyroid axis and is the main communication pathway from the brain to the thyroid – it functions to maintain normal levels of thyroid hormones in the body. 

Essentially when the hypothalamus senses low levels of thyroid hormone in the body it releases a thyrotropin-releasing hormone which stimulates TSH (thyroid-stimulating hormone) which stimulates the thyroid to release T4 and T3 (our main thyroid hormones) ensuring the body and thyroid stay in balance.

What impacts the HPT?

Many stimuli can impact the HPT axis including stress, blood sugar imbalance, high leptin, viruses, nutrient deficiencies, overeating and undereating, excess body weight, and low body weight.

So why is this important for hormone health?

As we know now, the thyroid impacts our sex hormones and can also mimic hormone imbalance too. Therefore anything that can disrupt the HPT axis can disrupt our hormones. 

It is important to rule out underlying thyroid imbalances and support the HPT when addressing hormone health.

Three key takeaways:

  • Support your blood sugar levels. This is one of the best ways to support the thyroid, HPT, and healthy hormones. Start by prioritising protein at every meal and incorporating a low carbohydrate breakfast such as eggs and vegetables or a protein smoothie with nuts and berries. 
  • Address your stress levels. This is one of the best ways to support your HPT axis,  even if you cannot remove major stressors from your life, you can start by changing the small stressors such as saying no to plans that don’t serve you, going to bed 30 minutes early to listen to calm music and getting to bed before 10.30 pm. 
  • Prioritise good quality sleep. Focus on getting 7-9 hours of sleep a night – this supports a stable HPT axis and healthy, happy hormones!

References:

Aghajanova, L., Lindeberg, M., Carlsson, I. B., Stavreus-Evers, A., Zhang, P., Scott, J. E., Hovatta, O., & Skjöldebrand-Sparre, L. (2009). Receptors for thyroid-stimulating hormone and thyroid hormones in human ovarian tissue. Reproductive biomedicine online, 18(3), 337–347. https://doi.org/10.1016/s1472-6483(10)60091-0

Cho M. K. (2015). Thyroid dysfunction and subfertility. Clinical and experimental reproductive medicine, 42(4), 131–135. https://doi.org/10.5653/cerm.2015.42.4.131

Csaba Fekete, Ronald M. Lechan, Central Regulation of Hypothalamic-Pituitary-Thyroid Axis Under Physiological and Pathophysiological Conditions, Endocrine Reviews, Volume 35, Issue 2, 1 April 2014, Pages 159–194, https://doi.org/10.1210/er.2013-1087

Mariotti S, Beck-Peccoz P. Physiology of the Hypothalamic-Pituitary-Thyroid Axis. [Updated 2021 Apr 20]. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK278958/

Ortiga-Carvalho, T. M., Chiamolera, M. I., Pazos-Moura, C. C., & Wondisford, F. E. (2016). Hypothalamus-Pituitary-Thyroid Axis. Comprehensive Physiology, 6(3), 1387–1428. https://doi.org/10.1002/cphy.c150027

Redmond G. P. (2004). Thyroid dysfunction and women’s reproductive health. Thyroid: official journal of the American Thyroid Association, 14 Suppl 1, S5–S15. https://doi.org/10.1089/105072504323024543

Saran, S., Gupta, B. S., Philip, R., Singh, K. S., Bende, S. A., Agroiya, P., & Agrawal, P. (2016). Effect of hypothyroidism on female reproductive hormones. Indian journal of endocrinology and metabolism, 20(1), 108–113. https://doi.org/10.4103/2230-8210.172245Singla, R., Gupta, Y., Khemani, M., & Aggarwal, S. (2015). Thyroid disorders and polycystic ovary syndrome: An emerging relationship. Indian journal of endocrinology and metabolism, 19(1), 25–29. https://doi.org/10.4103/2230-8210.146860

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