What causes thyroid problems? Learn more about the signs & symptoms & how you can manage an underactive or overactive thyroid


Your thyroid is a small, butterfly-shaped gland in the front of your neck, just above the voice box. It’s an internal regulator for your body’s metabolism, helping you control your heartbeat, energy levels, digestion, body temperature and even your thoughts and feelings with the thyroid hormones it produces.


Sometimes, people face an imbalance of these hormones which can result in thyroid conditions that need to be managed so your body is able to function normally.


What does my thyroid do?


Your thyroid creates two hormones – thyroxine (T4) and triiodothyronine (T3) – that travel through your bloodstream and act as chemical messengers to your cells and organs and regulate your metabolism.


Your brain helps to keep your levels in check by measuring the amount of thyroid hormones in the blood. If your levels are too low, your pituitary gland (which lies underneath your brain in your skull) produces thyroid stimulating hormone (TSH) to help encourage the thyroid gland to release more hormones. If your levels are too high, less TSH will be released by the pituitary gland. This process is how the levels of thyroid hormones in your blood are kept at the right level.


What are common thyroid problems?


The most common thyroid problems are an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism). Both come from an imbalance of or abnormal production of thyroid hormones.


Symptoms of thyroid problems begin very gradually, so, if you have any of these, you or your doctor may not notice any early warning signs until the condition has advanced. However, although they can be unpleasant or cause discomfort, most thyroid problems can be managed once properly diagnosed.


Underactive thyroid

What causes an underactive thyroid?


If there's too little thyroxine (T4) thyroid hormone in your blood, this will result in the mental and physical processes of your body slowing down. Both men and women can have an underactive thyroid, but it's more common in women. 


Most cases of an underactive thyroid are caused by the immune system attacking the thyroid gland and damaging it. It can also be caused as a result of treatment for thyroid cancer or an overactive thyroid. Less common causes of an underactive thyroid are an iodine deficiency (which is uncommon in the UK), problems with the pituitary gland or congenital hypothyroidism, which is when the thyroid gland doesn't develop properly in the womb.


What are the symptoms of an underactive thyroid?


The main symptoms of an underactive thyroid include:


• Fatigue and tiredness

• Weight gain

• Low mood or depression

• Feeling sensitive to the cold

• Dry skin and brittle hair

• Muscle weakness, cramps and aches

• A hoarse and croaky voice 

• Constipation

• ‘Pins and needles’ in the fingers and hands

• Irregular or heavy periods


The symptoms of an underactive thyroid are similar to those of other conditions, so the most accurate way to confirm if someone has an underactive thyroid is by taking a thyroid function test, where a sample of blood is tested to measure the hormone levels. If you're concerned that you may have an underactive thyroid, please seek advice from your GP. Thyroid test kits are also available to purchase via our Boots Online Doctor Thyroid Home Test Kit.*


What are the treatment options?


The most common treatment for an underactive thyroid involves taking daily hormone replacement tablets called levothyroxine to help raise the levels of thyroxine. When treatment is first started, regular blood testing will help the GP determine the correct dose, as this can take a little while to get right. Once the correct dose is established, blood tests are usually done once a year to monitor the thyroid hormone levels.


It’s likely that someone with an underactive thyroid will need to continue taking levothyroxine for the rest of their life, but with the correct dose, they should be able to lead a normal and healthy life.


Overactive thyroid

What causes an overactive thyroid?


An overactive thyroid is when there's too much T4 and T3 thyroid hormones in the blood. The condition can affect anyone, but it’s approximately 10 times more common in women than men, especially between the ages of 20 and 40 years.


There are a number of conditions that can result in an overactive thyroid, the most common being Graves’ disease, an immune system disorder that results in the overproduction of thyroid hormones. It could also be a result of thyroid nodules or an increased level of iodine in the body from taking prescription medications that contain iodine.


What are the symptoms?


The main symptoms of an overactive thyroid include:


• Nervousness, anxiety and irritability

• Mood swings

• Difficulty sleeping

• Persistent tiredness and muscle weakness 

• Sensitivity to heat 

• Swelling in the neck from an enlarged thyroid gland

• An irregular or unusually fast heart rate 

• Twitching or trembling 

• Weight loss


The symptoms of an overactive thyroid are similar to those of other conditions, so the most accurate way to confirm if someone has an overactive thyroid is by taking a thyroid function test, where a sample of blood is tested to measure the hormone levels. If you are concerned that you may have an overactive thyroid, please seek advice from your GP. Thyroid test kits are also available to purchase via our Boots Online Doctor Thyroid Home Test Kit.*


What are the treatment options?


Similarly to an underactive thyroid, an overactive thyroid can be managed. There are three main treatments that are usually recommended:


• Medicines called thionamides, which stop the thyroid from producing excess hormones. Once the thyroid hormone levels are under control, the dose may be gradually reduced and eventually stopped, however some people will need to take this medicine for several years or possibly for their lifetime

• Radioactive iodine treatment – a type of radiotherapy used to destroy the cells in the thyroid gland, limiting the amount of hormones it can produce

• Surgery – occasionally, surgery to remove part or all of the thyroid is recommended. If all of the thyroid gland is removed, then the person will need to take medicine for the rest of their life to provide the thyroid hormones their body requires


Each of these treatments has its benefits and drawbacks. A GP or specialist in hormone conditions (endocrinologist) will discuss the treatment options to determine the most appropriate one for the patient.


Are there any other thyroid problems?


Underactive and overactive thyroids are the most common thyroid conditions, but there are a small number of other disorders and conditions which can affect your thyroid. These can range from a goitre (an enlarged gland), thyroid nodules (solid or fluid-filled lumps within the thyroid) to thyroid cancer. If you're concerned about your thyroid, visit your GP.

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