Endogenous Hormones

About endogenous hormones

Hormones are chemicals that float around in the blood. They interact with receptors on cells to affect change in the body. You can think of them as keys, and the receptors as the mechanism leading to change within cells. So, if a hormone is responsible for absorbing sugar from the blood, it would float around until it finds a cell with a receptor that it can attach to. Once it attaches successfully it can ‘open the door’ and let the sugar into the cell!

In this article we will discuss some examples of endogenous hormones, however, please be aware that there are multitude of hormones and therefore not every endogenous hormone will be covered. If you have a query about a specific endogenous hormone, then you can search for more information on it in our health library. 

What Are Endogenous Hormones?

So, what are endogenous hormones? There are two broad groups that we can split hormones into exogenous and endogenous. Exogenous hormones are hormones that we take in from our diet. So, if you are prescribed medication that contains hormones these would be classed as exogenous hormones. Endogenous hormones, on the other hand, are hormones that are produced by your body. So, if you were to see something scary and your fight or flight response was activated, the adrenaline produced would be endogenous. Adrenaline is produced in the adrenal glands, which sit on top of your kidneys.

Examples of areas in the body where endogenous hormones are produced include:

• Pituitary gland - this is a gland located in the brain and produces a wide range of hormones including:
  • Growth hormone (GH)
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Follicle-stimulating hormone (FSH)
  • Luteinising hormone (LH)
  • Prolactin (PRL)
• Hypothalamus - this structure is also in the brain and produces hormones which are stored and secreted from the pituitary gland, including:
  • Oxytocin
  • Antidiuretic hormone (ADH)
  • Gonadotropin-releasing hormone (GnRH) 
• Thyroid gland - this releases thyroid hormones which help to regulate your body’s baseline functions
• Parathyroid gland - this releases hormones that help regulate the levels of calcium in your body
• Pancreas - this organ releases hormones that help with the regulation of sugar in the blood, such as:
  • Insulin
  • Glucagon 
• Adrenal glands - this gland releases hormones used for a variety of functions, including your fight or flight response, regulation of water concentration in the urine and also sugar levels! Examples of this include:
  • Cortisol
  • Adrenaline
  • Noradrenaline
  • Aldosterone
• Gonads (a.k.a the sex hormones) - these are produced by the reproductive system, depending on your anatomy, and can include the following:
  • Oestrogen 
  • Progesterone 
  • Inhibin 
  • Testosterone 

Conditions associatedd withh endogenouss hormoness

Endogenous hormones have a variety of functions within the body. It is essential for our bodily functions to have endogenous hormones. There are  few medical conditions associated with malfunctions of either the endogenous hormone production or the way the body reacts to the hormones. Abnormal levels of certain hormones (either exogenous or endogenous) can increase the risk of certain medical conditions. 

Cancers

Hormonal levels have been noted to have some bearing on the risk of someone getting breast cancer. Oestrogen and progesterone are  hormones that could have an impact on the risk of developing breast cancer. Oestrogen contributes to most of the physical changes we see in puberty. Progesterone contributes to the menstrual cycle and has a role in pregnancy. Examples of findings  include:

• An increase in breast cancer in females who use birth-control pills.
  • This risk goes back to baseline once the oral contraceptives are stopped
• Getting your first period early 
• Late menopause¹

The reason that early puberty and late menopause can increase your risk of breast cancer is that you are exposed to endogenous hormones for a longern)  leads to prolonged oestrogen exposure than someone who starts puberty later. In the same vein, if you go through menopause later in life then you will have more menstrual cycles, meaning that you are exposed to the endogenous hormones for a longer period than someone who goes through menopause earlier. 

There is a noted increase risk in ovarian cancer for people who use hormone replacement therapy. A prospective study showed an increased risk of ovarian cancer in postmenopausal people who used hormone replacement therapy.²

Similarly, there was a prospective study done looking at the link between sex hormones (oestrogen and progesterone) and endometrial cancer. It was found that there was an increased risk of endometrial cancer if someone was taking an oestrogen-only form of therapy. When there was a mix of oestrogen and progesterone-based therapy, the risk of endometrial cancer decreased or was delayed³. As such, it would appear that unopposed oestrogen can increase the risk of endometrial cancer. 

It’s important to remember that these are only a few of the risk factors associated with these types of cancers and that other risk factors will have an impact. It is usually a combination of risk factors that influence whether you suffer from any disease. If you have any concerns you should speak to a medical professional. 

Endocrine Conditions

There are a variety of medical conditions that are caused by either too little or too much of a hormone being produced. Examples of this include:

• Hyperthyroidism - too much of the thyroid hormones being produced. This can cause a variety of symptoms including sweating, palpitations and weight loss
• Hypothyroidism - too little of the thyroid hormones being produced. This can cause a variety of symptoms including slow heart rate, weight gain and tiredness
• Addison’s disease - this is due to a lack of cortisol and aldosterone. This can cause a variety of symptoms including muscle weakness, feeling thirsty and tiredness
• Cushing’s syndrome - this is due to too much cortisol. This can cause a variety of symptoms including easy bruising, deposition of fat in certain areas and high blood pressure

This list is not exhaustive, and if you have any concerns then you should contact a medical professional. 

Medical Uses

We know that hormones are essential for function, and dysfunction of these hormones can lead to an increased risk of certain health conditions. After understanding the role of an endogenous hormone, it is possible to use that information to create medication that can help in conditions where there is dysregulation of these hormones. Examples of medications that use hormones include:

• Oral contraceptives (hormonal contraceptives) - there are various forms of hormonal contraceptives. Common oral hormonal contraceptives include:
  • Combined oral contraceptive pill (aka ‘birth-control pill’). This has both sex hormones in it (oestrogen and progesterone). It works on a 21-day cycle, with a 7-day ‘rest’ period in which no tablets are taken. As such, there are 21 pills in the pack which contain sex hormones, and 7 pills which do not. The instructions on how to take the pills will usually be printed on the box they come in, or with the leaflet that they come with
  • Progestogen-only pill (aka ‘the mini pill’). This pill contains only progestogen. These are taken once a day and all of the pills have the active ingredient in them. They need to be taken at roughly the same time of the day, and come in two forms. One form needs to be taken within a 3-hour window, and the other needs to be taken within a 12-hour window
• Treatment for breast cancer 
• Treatment for ovarian cancer 
• Treatment for endometrial cancer

To determine if a cancer would be responsive to hormonal treatment, it is important to get a sample of it. This is usually done by taking a biopsy of the tissue that is suspected to be cancerous. This is sent to the lab and if they find receptors in the tumour cells that are responsive to hormones, then they know we can treat the cancer with hormonal therapy. 

Summary

Endogenous hormones are chemical messengers that float around the body, usually in the bloodstream. They act by reacting with receptors on cells to affect change. They play an important role in the way our bodies function. If there is an imbalance of these hormones it can lead to certain medical conditions. Endogenous hormones can also play a role in the development of certain medical conditions. For example an increase in breast cancer risk due to prolonged exposure to oestrogen. Having said this, once the cancer is identified it may be possible to treat it with hormonal therapy if the tumour is responsive to a specific hormone. 

Most importantly, if you have any concerns about your health you should consult with a medical health professional as each case is different and will need assessing by a professional before any diagnoses can be made.