Hormones are chemical messengers that are released into your blood where they travel to various organs, glands or tissues and tell them what to do.
Each hormone only affects specific cells (the building blocks of your tissues) to which they can bind, like a key fitting into a lock.
Hormones control everything from your metabolism, body temperature and blood sugar levels to your fertility, mood and sleep cycle. They are largely made by your endocrine system.
Most hormones in your body are made by your endocrine system; a group of organs and glands that include your kidneys, pancreas, hypothalamus and pineal gland in your brain, pituitary gland at the base of your brain, thyroid and parathyroid glands in your neck, and adrenal glands above your kidneys.
In women, the endocrine system also includes the ovaries and in men, the testes.
Oestrogen is a sex hormone that is produced by the ovaries in girls and women and by the testes in boys and men.
In girls, a rise in oestrogen levels triggers puberty and the development of breasts, the growth of pubic hair and other changes in the shape of the body.
After puberty, oestrogen is involved in regulating the menstrual cycle, pregnancy and maintaining bone density (strength). It also helps protect the heart, reducing the risk of heart disease in women.
In boys and men, oestrogen is involved in sex drive, erectile function and sperm development.
Testosterone is a sex hormone that is produced by the testes in boys and men and by the ovaries and adrenal glands in girls and women.
In girls and women, most testosterone is converted into oestrogen. Testosterone is also used to promote bone strength and maintain sex drive.
In boys, a rise in testosterone triggers puberty causing the testes to increase in size and drop lower, muscle mass to increase, a deepening of the voice and the growth of facial and pubic hair.
In men, testosterone is involved in maintaining sex drive, bone strength, muscle mass and sperm development. It also controls where fat is stored.
Insulin is made by beta cells in your pancreas and is responsible for controlling the levels of sugar in your blood. After eating a meal, causing your blood sugar levels to rise, insulin is produced. It tells your cells to absorb glucose, bringing your blood sugar levels back down.
Melatonin is made by your pineal gland in response to darkness. It helps you fall asleep and controls your body’s internal clock (circadian rhythm). It also promotes the production of immune cells for a healthy immune system.
Cortisol is made by your adrenal glands and controls your stress response, sleep-wake cycle and metabolism. It also can raise your blood pressure and blood sugar levels.
Human growth hormone is made by your pituitary gland and in children influences their height and the growth of their bones and other tissues.
In adults, human growth hormone affects muscle mass and metabolism. It helps raise your blood sugar levels when they get too low, reduces your fat storage and redistributes your fat.
Thyroid hormones are made by your thyroid glands and affect multiple systems in your body including your heart, muscles, hair, gut, brain and bones. They regulate your metabolism, heart rate, body temperature and how quickly food moves through your gut.
Hormonal imbalances occur when your body produces too much or too little of a hormone. A hormonal imbalance may be short-term or long-term (chronic) and can affect your quality of life to varying degrees.
Hormonal imbalances are responsible for a wide range of conditions and can be caused by lifestyle factors, genetics, trauma, stress, certain medications, steroids, tumours and autoimmune diseases.
Signs and symptoms of a hormonal imbalance vary depending on the particular hormone affected. Hormone imbalances are usually diagnosed using a blood test for changes in your hormone levels or other markers.
Depending on your symptoms and/or diagnosis you may be referred to a doctor who specialises in treating hormone-related conditions, an endocrinologist.
Diabetes occurs when levels of the hormone insulin in your body are too low. This can happen when the insulin-producing cells in your pancreas (beta cells) are worn out over time, as usually occurs in type 2 diabetes, or are mistakenly destroyed by your body’s immune system, as usually occurs in type 1 diabetes.
Diabetes is usually diagnosed using a blood test for glycated haemoglobin (HbA1c), which is a marker for your average blood sugar levels over the last two to three months.
If you’re diagnosed with type 1 diabetes, you will need to take daily insulin for the rest of your life, either via injections or via an implanted pump. If you’re diagnosed with type 2 diabetes, diet and lifestyle changes may be enough to control your blood sugar levels, although you may also need to take medication in the form of tablets (eg metformin) or insulin injections.
Thyroid disease occurs when your thyroid gland produces too little thyroid hormone, in which case you have an underactive thyroid (hypothyroidism), or too much thyroid hormone, in which case you have an overactive thyroid (hyperthyroidism). It is diagnosed using a hormone blood test.
Hypothyroidism usually develops gradually, with symptoms including achy muscles, dry skin and hair, fatigue, depression, sensitivity to the cold and unintentional weight gain.
In the UK, hypothyroidism is usually caused by your immune system mistakenly attacking your thyroid gland or by treatment for thyroid cancer or an overactive thyroid.
Hypothyroidism is treated by taking lifelong daily hormone replacement tablets (ie levothyroxine).
Hyperthyroidism causes sensitivity to heat, difficulty sleeping, mood swings, fatigue, unintentional weight loss, muscle weakness, twitching and heart palpitations. You may also notice swelling in your neck.
Hyperthyroidism is usually caused by Grave’s disease where your immune system triggers your thyroid gland to produce too much thyroid hormone.
Less commonly, it is caused by non-cancerous lumps on your thyroid glands, thyroid cancer, inflammation of your thyroid gland (thyroiditis) or a non-cancerous tumour on your pituitary gland (pituitary adenoma).
Hyperthyroidism is usually treated with medications, radioactive iodine treatment or surgery.
Polycystic ovary syndrome (PCOS)
Around one in 10 women in the UK have PCOS where small sacs filled with fluid (cysts) develop on the ovaries. These cysts cause the ovaries to produce excessively high levels of androgen hormones, such as testosterone.
PCOS often causes a lack of periods or irregular periods, as well as fertility problems. Other symptoms include excessive hair growth on the face, back, chest and buttocks, alongside hair loss from the head, as well as unintentional weight gain, and oily skin or acne.
It is usually diagnosed through a combination of analysing your symptoms, a hormone blood test and/or an ultrasound scan to check your ovaries for cysts.
Although PCOS can’t be cured, medications can treat many of the symptoms. If medication is not successful in improving your fertility, surgery may be recommended to temporarily destroy the androgen-producing tissue in your ovaries.
Hypogonadism in men occurs as a result of the testes not producing enough testosterone. Although it can occur from birth, this is rare, and it largely occurs in men over the age of 45 years (late-onset hypogonadism). Diabetes and being overweight or obese increases your risk of hypogonadism.
Symptoms include reduced sex drive, difficulty getting or maintaining an erection, shrinking of the testes, fatigue and reduced muscle mass. It can also lead to low mood, irritability and difficulty concentrating. Men with hypogonadism may also have fertility problems.
If you have symptoms of hypogonadism, your doctor will usually recommend a hormone blood test to check your testosterone levels. You may need further investigations to identify the cause of your low testosterone levels.
Causes include injury or infection of the testes, another hormone imbalance, treatment for cancer, steroid use, diabetes and/or obesity.
Treatment depends on the underlying cause but often involves hormone replacement therapy in the form of testosterone injections, gels, tablets, patches or pellets.
If you're concerned about symptoms you're experiencing or require further information on the subject, talk to a GP or see an expert consultant at your local Spire hospital.
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Lux has a BSc(Hons) in Neuroscience from UCL, a PhD in Cellular and Molecular Biology from the UCL Institute of Ophthalmology and experience as a postdoctoral researcher in developmental biology. She has a clear and extensive understanding of the biological and medical sciences. Having worked in scientific publishing for BioMed Central and as a writer for the UK’s Medical Research Council and the National University of Singapore, she is able to clearly communicate complex concepts.
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