What do hormones do?

Hormones play a role in many (often crucial) processes in our bodies. They regulate things like our energy and water levels, growth and reproductive functions as part of a finely balanced system. Various external factors and illnesses can throw the system out of balance.

Where are hormones made?

Most of our are made by endocrine glands, which then release them into our bloodstream. They then travel through the body to the parts where they’re needed. The main endocrine glands include the

Illustration: The main endocrine glands in the body – as described in the article

Substances known as local (or tissue ) are produced in individual cells, not in glands. They work exactly where they’re needed by having an effect on neighboring cells.

Some organs also produce in addition to doing their main job. One example is the kidneys, which make the hormone erythropoietin (EPO) as well as cleansing our blood. EPO stimulates the production of blood cells in our bone marrow. The nervous system can also affect our hormone levels.

A finely balanced regulation system

Our hormone levels are finely balanced to make sure they can regulate the processes in our body according to what is needed. A good example is the hormone insulin. It is produced in the and regulates our blood sugar levels.

Insulin ensures that the sugar in our blood gets into our cells. They use it for energy. But our blood sugar levels vary depending on what we eat and when we eat it. The reacts to these changes exactly as needed: It releases more insulin if there’s too much sugar in the bloodstream, and less insulin if there’s not enough blood sugar.

Often, a hormone regulates more than just one body function. One example is when there’s a lot of sugar in someone’s blood: The insulin that is released to bring the sugar levels back down also stops the body from burning fat. As a result, the cells use the sugar for energy first.

Hormones work together

Sometimes two different have opposite effects, like insulin and glucagon. Glucagon is made in the too but it’s only released if there’s not enough sugar in the blood. This happens when someone fasts (doesn't eat anything for some time), for example. Glucagon makes our muscles and liver release stored sugar into our bloodstream so that our body's cells are always supplied with energy.

Thyroid hormone production: Negative feedback loop – as described in the article

Often, that are higher up in the “hormone hierarchy” regulate how much of another hormone is released. Many of these higher-ranking are produced in the pituitary gland and the hypothalamus in the brain. This type of regulation is often based on a negative feedback loop. For instance, the pituitary gland reacts to the thyroid hormone levels in our blood: If they’re too low, the pituitary gland releases TSH (thyroid-stimulating hormone, also called thyrotropin), and that makes the thyroid produce more . When the thyroid hormone levels in the blood increase, the pituitary gland releases less TSH.

Which hormones regulate the different body functions?

Our hormonal system (endocrine system) is complicated: Each hormone has its own specific functions, but often regulates a process in the body together with other . And each hormone can affect several other processes too.

Energy levels

The insulin produced by the ensures that cells can absorb sugar for energy. But other , particularly the thyroid T3 and T4, are also involved. They trigger metabolic processes (chemical reactions in our body), which use up energy and sugar. These processes may raise your body temperature and increase your heart rate, for example.

Our “stress ” increase the amount of energy our bodies use up too. One well-known example is adrenaline (also called epinephrine). When we’re frightened or doing something strenuous, the adrenal glands release adrenaline into our blood. This hormone increases our pulse and blood pressure. It also causes sugar and fat to be released so that it can be used for energy. Glucocorticoids, which are produced in the adrenal cortex, have similar effects. Cortisol is a well-known glucocorticoid hormone. It is used as a steroid medication to treat various health complaints. The human growth hormone somatotropin, which is made in the pituitary gland, affects our energy levels too.

Water and salt levels

The kidneys remove water and salts from our bodies by releasing them into our urine. Hormones such as adolsterone help regulate the water and salt removal process, which has an effect on blood pressure. Adolsterone is made in the adrenal cortex too. But the renin and angiotensin also play a role. Another hormone that’s involved comes from the hypothalamus in the brain. Known as anti-diuretic hormone (ADH) or , it can reduce the amount of urine a person passes when necessary.

Bone metabolism

Our bodies need and phosphate for a process known as “bone metabolism.” These minerals also have other functions in the body. In the bones they are like bricks that are inserted when bone tissue grows, or removed from existing bones if they’re needed elsewhere. Hormones ensure a healthy balance here: The parathyroid glands produce a hormone called “parathyroid hormone." One of its jobs is to promote the breakdown of bone tissue and increase blood levels. Calcitonin, a hormone made in the thyroid gland, can bring levels back down. Other involved in bone metabolism include the growth and sex . Vitamin D plays a role too. For example, it controls how much our bowel absorbs from what we eat.

Development and sexuality

Growth like somatotropin stimulate cell division and cell growth, as well as having an effect on our bodies’ energy and water levels. By doing this, they help the body grow. When puberty starts, the sex begin to affect our bodies too. The male sex hormone testosterone, which is made in the testicles, promotes muscle growth and body hair growth, for example.

The female sex hormone estrogen, which comes from the ovaries, makes the mammary glands in the breasts grow, among other things. The sex make our reproductive organs develop and start working. In women, they also control the menstrual cycle and the physical changes during pregnancy. Another important task these have is making us feel sexual desire.

It is worth noting that sex aren’t only produced in the testicles and ovaries. Smaller amounts are also made in the adrenal glands, the liver, fatty tissue and our skin, which is why men also produce estrogen and women produce testosterone.

What happens when our hormonal system is thrown out of balance?

Various health problems are due to the body having

  • too much,
  • too little
  • or a complete lack

of a particular hormone.

A typical example of the “too much” problem is an overactive thyroid gland (hyperthyroidism), which results in too many thyroid . This causes the metabolism to go into overdrive, which can lead to a rapid heartbeat, diarrhea and/or weight loss.

An underactive thyroid (hypothyroidism), on the other hand, means the thyroid doesn’t produce enough of these . This can result in tiredness and a drop in physical fitness.

One example of a disease where there's a lack of a hormone is type 1 diabetes. Here the either produces just a very small amount of insulin or none at all.

Sometimes, the problem is related to how well a hormone works rather than how much of it there is. This happens at the beginning of type 2 diabetes, for instance: The does produce insulin but the cells stop reacting to it and don’t take in enough sugar from the blood. This results in a rise in blood sugar levels.

Hormones are also used as medication, like insulin in the treatment of diabetes. If a person’s body makes too much of a hormone, they can take medication to reduce the level. For example, anti-thyroid drugs reduce the amount of thyroid produced. Another medical use of is contraception. The birth control pill ("the pill") works by changing the woman’s hormone levels to stop her ovaries from releasing an egg.

Brandes R, Lang F, Schmidt R (Ed). Physiologie des Menschen: mit Pathophysiologie. Berlin: Springer; 2019.

Lippert H. Lehrbuch Anatomie. München: Urban und Fischer; 2017.

Menche N (Ed). Biologie Anatomie Physiologie. München: Urban und Fischer; 2016.

Pschyrembel Online. 2022.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

Comment on this page

What would you like to share with us?

We welcome any feedback and ideas - either via our form or by gi-kontakt@iqwig.de. We will review, but not publish, your ratings and comments. Your information will of course be treated confidentially. Fields marked with an asterisk (*) are required fields.

Please note that we do not provide individual advice on matters of health. You can read about where to find help and support in Germany in our information “How can I find self-help groups and information centers?

Über diese Seite

Created on January 10, 2022

Next planned update: 2025


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

How we keep you informed

Follow us on Twitter or subscribe to our newsletter or newsfeed. You can find all of our films online on YouTube.