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Overactive Thyroid

An overactive thyroid gland produces too much thyroid hormone. This can cause a wide range of symptoms of varying severity.

What is an overactive thyroid?

An overactive thyroid, also known as hyperthyroidism or thyrotoxicosis, is a condition in which the thyroid gland produces too much thyroid hormone.

The thyroid is a small, butterfly-shaped gland in the neck, just in front of the windpipe. It produces hormones to help regulate your body.

Too much of this hormone can affect your entire body and cause a range of symptoms, which can vary in severity.

What are the symptoms of an overactive thyroid?

There are a wide range of symptoms of an overactive thyroid. These are some of the more common symptoms:

  • Nervousness, anxiety and irritability
  • Hyperactivity
  • Swelling in the base of the neck caused by an enlarged thyroid gland (goitre)
  • Irregular and/or unusually fast heart rate (palpitations or arrhythmia)
  • Mood swings
  • Sleep changes
  • Menstrual changes
  • Fatigue and muscle weakness, including tremors and twitches
  • Sensitivity to heat, as well as warm skin and sweating
  • Muscle weakness
  • Diarrhoea and changes in bowel movements
  • Needing to pass urine more often than usual
  • Persistent thirst
  • Itchiness and rash, also known as hives
  • Fine, brittle hair and hair loss
  • Unintended weight loss, despite increased appetite
  • Eye problems (usually related to Graves’ disease, also known as Graves’ ophthalmopathy)

An overactive thyroid can cause further, more severe complications especially if it is not well controlled. If you are concerned about your symptoms, you should visit your GP.

What causes an overactive thyroid?

There are several reasons why you might have an overactive thyroid:

  • Graves’ disease (an autoimmune condition)
  • Plummer’s disease (overactivity in a pre-exisiting nodular goitre)
  • A single overactive nodule in the thyroid
  • Medication, such as amiodarone
  • High levels of human chorionic gonadotrophin, which can occur in pregnancy
  • Pituitary gland tumour
  • Consuming excess iodine

Risk factors include:

  • Family history
  • Being female
  • Certain chronic conditions including Type 1 diabetes, pernicious anaemia and primary adrenal insufficiency (Addison’s disease)
  • Having a lot of iodine in your diet
  • Being pregnant

How is an overactive thyroid assessed?

If you have been experiencing symptoms, you should speak to your GP or seek an opinion from an endocrinologist (doctor specialising in hormonal disorders) .  It’s important to accurately assess your symptoms, as they can be associated with a number of other conditions.

At your appointment, you will be asked about your symptoms, other medical conditions, medication, family history and other factors such as your work and whether you smoke cigarettes. Your GP or Consultant may do a physical examination of your neck, as well as examine other areas of your body that have been affected.

If they think there is a thyroid issue, they will arrange for a blood test, which will let them know how well your thyroid is working.

If your thyroid hormone levels are high, your GP may manage this or you may be referred for further tests, including further blood tests, and treatment.

If more investigation is needed a thyroid scan may also be recommended.

How is an overactive thyroid treated?

Sometimes, treatment is not required as the hyperthyroidism will self-correct in a short period of time.  During this time, if needed, symptoms can be controlled with medication such as a beta-blocker.

The main treatments are:

  • Medication (eg anti-thyroid drugs such as carbimazole)
  • Radioiodine treatment – a type of radiation which destroys cells in the thyroid to reduce its ability to produce hormones (this is not suitable for pregnant or breast feeding women and some people with severe thyroid eye disease)
  • Surgery to remove your thyroid (thyroidectomy)

If you’re unsure what treatment you should go for, or the above treatments don’t work for you, our team of expert specialists are here to help.

This content has been checked and approved by

Miss Aimee Di Marco  ›

Miss Aimee Di Marco is an Endocrine Surgeon at King Edward VII’s Hospital.

Find your specialist in overactive thyroids at King Edward VII's Hospital

Dr Malcolm Prentice  ›
Special interests include:
Diabetes (+ 18) more
Miss Aimee Di Marco  ›
Special interests include:
Parathyroid surgery (+ 11) more

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