What is the thyroid and what is it responsible for?

Written by: Dr Mark Vanderpump
Published: | Updated: 29/06/2023
Edited by: Bronwen Griffiths

The thyroid gland is located in the neck and is needed to regulate the metabolism of all cells in the body. Therefore, when something goes wrong with the thyroid, chances are, you will notice that something isn't right. Dr Mark Vanderpump, a top consultant endocrinologist, explains the most common thyroid disorders (hyperthyroidism, hypothyroidism and thyroid nodules).



What is the thyroid?


The thyroid is a butterfly-shaped gland, which is situated just below your Adam’s apple (the larynx). A normal thyroid gland is neither visible nor can be felt if you apply finger pressure to your neck. It is the thyroid gland's job to produce hormones which regulate the metabolism of virtually all the cells in your body. This includes your temperature, heart rate, blood pressure and metabolism. It does this by producing two thyroid hormones - T3 and T4.


When there is too much thyroid hormone in the bloodstream it causes a condition called hyperthyroidism. When there is too little it is called hypothyroidism.




This occurs when when your thyroid is overactive, about 1 in 100 people in the UK have this condition and it is six times more common in women.


As individual hyperthyroidism symptoms could relate to many other conditions, it’s not unusual for diagnosis to take 3-6 months - during which time you may have felt quite unwell.


Symptoms of hyperthyroidism

Signs of hyperthyroidism


Shaky and hot hands

Heat intolerance

Fast or irregular heartbeat


Inability to sit still

Weight loss despite good appetite

Flushing of the face and trunk


Fast tendon reflexes

Inappropriate anxiety

Enlarged thyroid gland (goitre)

Palpitations of the heart

Prominent or bulging eyes

Shortness of breath


Tetchiness and agitation


Poor sleep



Around ninety per cent of hyperthyroidism is caused by an autoimmune condition known as Graves’ disease. In Graves’ disease, antibodies stimulate thyroid cells to increase thyroid hormone production. Often, the thyroid becomes enlarged and becomes visible externally at which point it is known as a goitre. You can read more about goitres in my other detailed article on the topic. 


One third of those with Graves’ disease also develop a variety of eye problems (orbitopathy), including a staring appearance, grittiness, soreness, protruding eyeballs and, rarely, double vision or sight problems.


Other causes include benign thyroid nodules (nodular goitre), which are more common as we get older, or a temporary thyroid inflammation (thyroiditis) due to a virus or autoimmunity.


According to its type, hyperthyroidism and its side effects are usually treated with a combination of antithyroid drugs, radioiodine therapy, beta-blockers and, in some cases, surgery.




If you have this condition, it means that you have an underactive thyroid which will then slow down your body’s metabolism. About 2 in 100 people in the UK have hypothyroidism and it is ten times more common in women.


Symptoms of hypothyroidism

Signs of hypothyroidism

Fatigue and lethargy

Puffy face

Cold sensitivity

Cool dry skin

Dry skin

Slow pulse rate

Loss of scalp hair

Thinning of the hair including eyebrows

Impaired concentration and memory

Slow tendon reflex relaxation time

Increased weight

Hoarse voice



Hoarse voice


Tingling of the hands


Heavy periods





Approximately seventy-five per cent of hypothyroidism is caused by an autoimmune condition called Hashimoto’s (whereby a goitre can also develop). The remainder are due to successful treatment of thyroid cancer, or an overactive thyroid which has then resulted in a far less dangerous underactive thyroid.


Early diagnosis of this condition is possible through greater awareness and an increased availability of blood tests. The current standard treatment is via the synthetic form of T4 called Levothyroxine which normalises and maintains the thyroid hormone levels.


Thyroid nodules


Appearing on their own or in clusters, a thyroid nodule is a solid or fluid-filled lump which can be caused by several different things:

  • Lack of iodine in your diet in early childhood
  • Abnormal growth of thyroid cells within your thyroid gland (a hyperplastic or colloid nodule)
  • Thyroid adenoma (a benign tumour)
  • A multinodular goitre comprising several nodules
  • Thyroid cancer (those at highest risk are extremes of age (below 20 or above 70 years) and men more than women)


More than ninety-five per cent of thyroid nodules are harmless or benign. Thyroid nodules are more common in women and are more likely to occur as we age. Although most nodules don’t cause symptoms, they can become so large that they can be felt, seen or cause breathlessness or difficulty in swallowing as they press on your windpipe or oesophagus. In rare cases, there may even be hoarseness or difficulty speaking because of compression of a large nodule on the larynx.


Some nodules are described as “hot”, producing extra thyroid hormone which can then cause symptoms of hyperthyroidism. You can read more about thyroid nodules in my other article on the condition.


A few nodules are malignant, but most are slow growing and small when found. Aggressive thyroid cancer is uncommon but these nodules will be large, firm, fixed and fast growing. An ultrasound scan will be used to establish the size and number of nodules and whether a fine needle aspiration cytology (FNAC) to remove cells for microscopic examination will be required. This will help to decide whether it is benign or malignant. Sometimes the tests are not reassuring enough to give a definitive answer so surgery or ultrasound surveillance is advised.


If the tests reveal that the nodule/nodules are not causing any problems and are benign, then no further action is required unless there is evidence of increased growth of the nodule. Benign nodules can get bigger, but treatment is rarely required unless they are causing significant compression symptoms in the neck. A cancerous nodule will be removed surgically and you may then be treated with radioactive iodine. Around 90% of those identified with thyroid cancer will have a positive outcome.


Occurrence of thyroid nodules does tend to run in families and in those who have had an early childhood in areas that have been iodine deficient in the past, including Europe.




Dr Mark Vanderpump works in several top London medical institutes, including the Hospital of St John and St Elizabeth and The Platinum Medical Centre. To make an appointment with Dr Vanderpump, visit his Top Doctors profile.

By Dr Mark Vanderpump
Endocrinology, diabetes & metabolism

Dr Mark Vanderpump is a highly experienced consultant endocrinologist based in London who specialises in adrenal gland disorders, hyperparathyroidism and hyperthyroidism alongside hypothyroidism, thyroid disorders and diabetes. Furthermore he has significant expertise in treating polycystic ovaries (PCOS). He practices at The Physicians' Clinic, Wellington Diagnostics & Outpatients Centre and One Welbeck Digestive Health clinic.

Dr Vanderpump has had a career spanning over 30 years, and was previously a consultant physician and honorary senior lecturer in endocrinology and diabetes at the Royal Free London NHS Foundation Trust. His main area of expertise is thyroid disease, but his clinical practice includes all aspects of diabetes and endocrinology. He also sees referrals of less frequently-occurring conditions such as thyroid cancer; pituitary conditions such as acromegaly; and adrenal disorders including Addison's disease, plus calcium and bone disorders.

Dr Vanderpump, who is highly qualified with an MBChB, MRCP and MD alongside a CCST and FRCP, did higher training in the West Midlands, North East England and North Staffordshire.

Dr Vanderpump is a respected figurehead in the endocrinology community. He is the former president of the British Thyroid Association and former chair of the London Consultants' Association.

He continues to lecture on diabetes and thyroid disease, is widely published in peer-reviewed journals and has published a book called Thyroid Disease (The Facts). He is also a member of the Royal College of Physicians (RCP), where he is also a fellow, the British Thyroid Association (BTA) and the Society of Endocrinology (SoE). Furthermore, he has professional membership of the Association of British Clinical Diabetologists (ABCD) , London Consultants' Association and the Independent Doctors Federation.   

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