The Endocrine System – a system of hormonal balances

The hormone system of your body is called the endocrine system. It is a collection of hormone producing glands and cells in different parts of your body.

What are hormones?

Hormones are complex messenger chemicals that are released into the bloodstream by endocrine glands. They target specific cells and tissues and alter their activity, to regulate body functions, such as metabolism, growth and sexual reproduction.

What’s in a hormone?

Hormones are made up of molecules from steroids, proteins or an amino acid called tyrosine. A hormone doesn’t become active until it is bound to a specific receptor on a cell or inside it. Hormones from proteins bind to receptors on the outside of the cell membrane. Hormones from steriods and tyrosine pass inside the cell and bind to receptors in the cytoplasm or the nucleus.

What are the main endocrine glands?

Thyroid Gland

The thyroid is located around your trachea (the windpipe). It releases a hormone called thyroxine which targets your body’s cells to increase your metabolic rate (the rate at which oxygen is used to release energy from glucose). The thyroid gland controls not just metabolism but also body weight, the rate of energy use and heart rate. Unlike most other glands, it can store thyroxine.

Parathyroid Glands

These are four small glands located on the back of the thyroid gland. They release parathyroid hormone which increases levels of calcium in your blood. Calcium is necessary for healthy bones and teeth, as well as to ensure muscles and nerves work properly.

Adrenal Glands

You have two adrenal glands located on top of your kidneys. The adrenal cortex is the outer part and makes several hormones that control metabolism in cells as well as salt levels in body fluids. The inner part is called the adrenal medulla. It produces adrenalin, which helps you respond to stress.

The hormone cortisol is produced by the middle layer of the adrenal cortex. It is a stress hormone and is vital to our survival. It helps maintain blood pressure, glucose levels, controls how the body utilises fat, protein, carbohydrates and minerals and it also helps reduce inflammation. When we are under stress, it is produced in larger amounts.

Pineal Gland

The pineal gland regulates your body’s internal clock by releasing varying amounts of melatonin. You have higher levels of melatonin at night, to make you feel sleepy, and lower amounts during the day.

Pituitary Gland

This “master” gland is the size of a raisin and releases eight hormones. It controls the activities of many other endocrine glands and cells. The pituitary gland hangs from the base of the brain and is attached by a short stalk to the hypothalamus, an area of the brain that controls pituitary function. Pituitary hormones control growth, metabolism and reproduction, either directly or by making other glands release hormones.

The anterior (front) of the pituitary gland produces the hormone prolactin (which stimulates breast milk production after giving birth). It also affects sex hormone levels in ovaries and testes as well as fertility.

Growth hormone stimulates growth in childhood. In adults it is important for maintaining bone and muscle mass. It also affects fat distribution in the body.

Adrenocorticotropin stimulates the production of cortisol by the adrenal glands.

Thyroid-stimulating hormone stimulates the thyroid gland to produce thyroid hormones.

Luteinising hormone stimulates testosterone production in men and ovulation in women.

Follicle-stimulating hormone promotes sperm production in men and stimulates the ovaries to produce oestrogen and develop eggs in women. Luteinising hormone and follicle-stimulating hormone work together to enable normal function of the ovaries and testes.

The posterior (back) of the pituitary gland is where the following hormones are stored:

Antidiuretic hormone (vasopressin) regulates water balance in the body. It conserves body water by reducing the amount of water lost in urine.

Oxytocin causes milk to flow from the breasts in breastfeeding women and may help labour to progress.

Thymus Gland

The thymus gland releases hormones that are essential for the development of lymphocytes, which have the ability to identify invading organisms and are therefore essential to a healthy immune system.


The pancreas releases two hormones which control glucose levels in your blood. One hormone is insulin, which decreases glucose levels. The other hormone is glucagon, which increases glucose levels. Together, they regulate your glucose levels, so you can have enough energy during the day, even when you’re very active.


Eggs are released by the ovaries in adult women. Ovaries also produce the female sex hormones, oestrogen and progesterone, which produce female features and control the menstrual cycle.


The testes make sperm in adult men and also release the male sex hormone testosterone, which stimulates sperm production in the testes and also produces adult male features, including increased facial and body hair and muscular body shape.

Other parts of the body that release hormones

The hypothalamus is a cluster of nerve cells at the base of the brain. Through its connection to the pituitary gland, this part of the brain provides a link between the endocrine system and nervous system. The hypthalamus makes hormones that control the release of hormones from the pituitary gland.

The heart releases a hormone called atriopeptin that controls blood pressure.

The stomach wall releases a hormone that aids digestion.

The kidneys make a hormone called erythropoietin, that increases production of red blood cells in bone marrow.

The small intestine releases hormones that stimulate digestion.

What is adrenal fatigue?

Adrenal fatigue is not a proven medical condition. Symptoms are supposedly trouble falling asleep, chronic fatigue and trouble thinking clearly or finishing tasks (which is natural if you were exhausted). These are common symptoms and could be due to other health problems or just happen during our normal busy lives.

Fatigue can be due to poor sleep habits (which is very common nowadays), stress, poor diet, depression, anaemia, arthritis or diabetes. Because chronic fatigue may be due to another condition, it is important that you see your doctor for a diagnosis rather than a complementary therapist. A therapist (even a nutritionist) may simply sell you a series of supplements or suggest food intolerance tests that is unlikely to get to the cause of the problem.

There is no test to detect adrenal fatigue that is based on scientific facts. If you are offered a blood or saliva test, you’re paying for results that have no basis in science.

There is a danger in taking adrenal hormone supplements as your adrenal glands may stop working and become unable to make adrenaline when needed. If this happens, your adrenal glands can become inactive for a period of time after you stop taking supplements. There is also the risk of developing a life-threatening condition called adrenal crisis.

What is Wilson’s Temperature Syndrome?

I hadn’t heard of this before I started doing research for this post, but I have seen posts about it from people who believe they have it and you can buy books in the UK purporting to help if you have it, so here’s some information in case a complementary therapist diagnoses you with it.

As with adrenal fatigue, the symptoms are non-specific enough to be part of other health problems and include low body temperature and slowing metabolism, caused by illness or stress. It was a theory developed by a Dr Wilson in 1990 who says it represents a thyroid hormone deficiency, even though low hormone levels are not detected in blood tests. This is not an accepted condition and is totally unproven.

And finally

I hope this has helped you understand a little more about how your endocrine system works. If part of the system isn’t working, your doctor may send you for blood tests or to see an endocrinologist, who specialises in the endocrine system. It’s never a good idea to see a complementary therapist for treatment of a complex system of the body. Should you trust your health to someone who may only have completed a short course in selling supplements and tests and tell you about unproven theories, rather than a medical professional who has years of experience and is able to diagnose whether you have a potentially serious condition? As someone who works in the same building as other therapists and who sees how quickly they add new “therapies” to their practices, I would never see a complementary therapist for a medical condition. Give me a doctor, every time.