The HPO Axis and your hormones

The HPO Axis

Hormone production starts in the brain. So in order to understand exactly how stress impacts our hormones and our cycles, it is important to look closely at the communication pathway from the brain to your ovaries. This is called the HPO axis or hypothalamus-pituitary-ovarian axis. 

What is the HPO Axis?

The HPO axis is the communication pathway from your brain to your ovaries, and is comprised of the following: 

  • Hypothalamus – This is part of the brain responsible for maintaining balance in the body. One of its main roles is connecting the nervous system and endocrine system. 
  • Pituitary gland – Influencing all parts of the body, the pituitary gland has a major role in hormone function by telling other glands to release certain amounts of hormones. 
  • Ovaries – The ovaries are the primary female reproductive organs. They have many important functions including the secretion of hormones and releasing of eggs for possible fertilisation each month. 

What does a balanced HPO axis look like?

The HPO axis, when in balance, means proper signalling is occurring between the brain and the ovaries. This results in progesterone and oestrogen levels that are balanced, regular periods and regular, healthy ovulation.

Let’s look in more detail at how it works.

  1. It starts with the hypothalamus. The hypothalamus releases something called gonadotropin releasing hormone (GnRH). 
  2. Then it moves to the pituitary gland. The GnRH then instructs the pituitary gland to make luteinising hormone (LH) and follicle stimulating hormone (FSH).
  3. FSH encourages healthy development of the egg in the ovary and causes oestrogen to rise.
  4. LH plays a vital role in the maturation of the egg and causes ovulation to occur. 
  5. Both FSH and LH bind to ovarian receptors and signal the release of oestrogen and progesterone. 

Therefore the release of progesterone and oestrogen are determined by the communication from the brain to the ovaries. When this signalling system is in balance then your hormones and cycle are likely to be in balance too. 

A well functioning HPO Axis

The main hormonal fluctuations involved in a healthy, menstrual cycle when the HPO axis is working well.

What happens when IT is out of balance?

When the body or mind is experiencing stress, the stress response ensures that above all else, survival is the utmost priority. This means that less essential functions such as reproduction are deprioritised.

Under any kind of stress the HPO axis can become dysregulated. 

High cortisol can lower GNRH which leads to lower FSH and LH. As a result the production of oestrogen, progesterone and testosterone can go a bit haywire. 

This means the communication pathway from the brain to the ovaries is no longer balanced and well functioning. Most commonly this leads to imbalance in progesterone and oestrogen, and typically impaired ovulation and irregular periods. 

What kind of stress impacts the HPO axis?

Stress can be external or internal and can be physical, mental, emotional and even spiritual too. This is important to note as we may not always realise that we are under stress. Let’s look at different types of external and internal stressors.

  • External stress: Work stress, family commitments, relationships, busy cities, light and noise pollution, loss, societal pressure, bills, social media and more. 
  • Internal stress: Hormone imbalance, parasites, underlying viruses, lack of sleep, caffeine intake, alcohol intake, negative thoughts, excessive exercise, under or over eating and more. 

This gives you an idea of all the types of stress that can impact your ovaries and hormone health, and therefore cause irregular or missing periods as well as hormone imbalance. 

What else can cause HPO axis dysfunction?

We know stress is one of the biggest disruptors of the HPO axis. But it is important to look closer at the main types of stress that can disrupt this communication pathway.

1. Blood sugar imbalance and insulin resistance

You may be surprised to learn that blood sugar imbalance is considered a form of stress for the body. 

When our blood sugar rises, and then subsequently falls, it can increase inflammation and stimulate cortisol release. This signals to the body that we are in a state of survival (fight or flight) and that it is not safe to regulate our sex hormones. Therefore stress hormones increase and sex hormones decrease. Blood sugar balance is vital for healthy hormones.

When blood sugar is continuously out of balance, it can put us at risk of developing insulin resistance. And insulin resistance is the most common driver of polycystic ovarian syndrome (PCOS), driving an estimated 70% of cases.

Read more about insulin resistance and hormones.

2. Weight

Both being overweight or underweight are a form of stress on the body. Both can impact the HPO axis and cause imbalance in the regulation of ovulation. 

Being overweight can cause a loss of normal GnRH pulsatility, which in turn can impact the release of LH and FSH from the pituitary gland, finally resulting in hormone imbalances. 

Being underweight is also a common cause of HPO axis dysregulation and can be a common cause of hypothalamic amenorrhea (HA). HA is when a woman doesn’t get a period due to low intake of energy (under eating) or high use of energy (over exercise). 

Read more about the symptoms of Hypothalamic Amenorrhoea. 

3. Over exercise

One of the most common causes of HPO axis dysregulation and therefore missing periods (also known as hypothalamic amenorrhea) is over exercise. 

It is common for many athletes to lose their periods, but it is also common for many women who enjoy frequent HIIT workouts and cardio to experience this too, as it is a form of stress on the body. 

Research has showed that there is an increased risk of anovulation (lack of ovulation) in extremely heavy exercisers who undertake more than 60 minutes of high intensity or cardio exercise every day.

4. Hormonal Contraception

Hormonal contraception such as the oral contraceptive pill, implantation and injections disrupt the HPO axis. 

This is because the synthetic hormones in these contraception methods cause the HPO axis to shut down. This is one of the reasons it can take up to 1 year for a normal cycle to return when finishing hormonal contraception – it takes time for the HPO axis to communicate properly again and reestablish a healthy and regular cycle.

5. HPO axis and PCOS

Polycystic ovarian syndrome (PCOS) is a syndrome that has connections to reproductive, endocrine and metabolic dysfunction. Typically defined by its symptoms of missing or irregular periods, excess hair growth, weight gain and acne. It is common in PCOS to find increased GnRH pulsations and increased production of LH. This leads to poor oocyte development and lack of ovulation. When there is disturbed ovarian-pituitary and hypothalamic feedback due to stress of any kind it can worsen the gonadotrophin abnormalities which can in turn make PCOS worse. 

Read more about the signs and symptoms PCOS.

Our recommended treatment approach

Check your HPO axis function

At FUTURE WOMAN we look to treat any dysregulation to the HPO axis by first testing your hormones at home and then providing you with a personalised health plan based on your results.

Our most popular test for symptoms of a dysregulated HPO axis is our Advanced Hormone Test. In this dried urine and saliva test, we can assess both your metabolised cortisol and cortisone (your main stress hormones). This helps to understand the functioning of the adrenal glands and how stress may be impacting the body. This test also assess your oestrogen and progesterone and their metabolites to show us what is happening with your sex hormones in the body. This helps to form a clearer picture of your overall hormone health so we can create your personalised plan to help to bring your hormones, stress and health back into balance.

Want to speak with an expert?

Book in for a FREE 15 minute consultation with a FUTURE WOMAN practitioner.

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