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Thyroid Statistics UK – How Many Suffer from Under-active or Overactive Thyroid Problems?

Author: Forth

March 2, 2020

Reviewed by: Dr Thom Phillips

General wellbeing

Image of the thyroid in a person's neck

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There are suggestions that the prevalence of some thyroid disorders is on the rise and so too are the number of prescriptions for thyroid hormones. In this blog we look at the statistics to see just how big thyroid issues are in the UK.

How many people in the UK have a thyroid problem?

We used a combination of our own internal data, NHS prescription data and Google Search data for this piece of research.

When looking at the statistics surrounding thyroid problems, it is easier to split them into their corresponding conditions. The standard test if either condition is suspected is blood thyroid stimulating hormone (TSH) levels.

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Overactive thyroid

The NHS estimates that one in 50 women live with an overactive thyroid gland or hyperthyroidism.  Women are also six times more likely to have an overactive thyroid gland than men.

This is borne out by data collected by home blooding testing service Forth, which highlights the higher incidence of an overactive thyroid in women compared to men. When hyperthyroidism is diagnosed, the thyroid gland produces increased amounts of thyroid hormones and thyroid-stimulating hormone (TSH) production is suppressed, so circulating levels will be low.

Table 1. Low thyroid-stimulating hormone levels according to age and gender.

Male Results by Age Reference Range % low or borderline low
20-29 0.27-4.2 0.00%
30-39 0.27-4.2 0.18%
40-49 0.27-4.2 0.00%
50-59 0.27-4.2 0.43%
Female Results by Age Reference Range % low or borderline low
20-29 0.27-4.2 0.00%
30-39 0.27-4.2 1.75%
40-49 0.27-4.2 1.93%
50-59 0.27-4.2 2.35%
60-69 0.27-4.2 13.56%

Underactive thyroid

The prevalence of an underactive thyroid is 2% in the UK. An underactive thyroid is also ten times more common in women, but it can affect both genders. Children and babies can also have an underactive thyroid, with some babies born with the condition. When an underactive thyroid is suspected, TSH levels increase while the levels of thyroid hormones decrease.

The menopause and the thyroid gland

The menopause is a natural part of ageing in the female life cycle and induces many physiological and emotional changes.

The incidence of thyroid disease including hypothyroidism is highest among postmenopausal women. Often the diagnosis of a thyroid problem in this demographic is difficult because the symptoms are like those of the menopause and ageing in general.


Our results show that in 13.26 per cent of post-menopausal women, TSH levels are high and 6.78 per cent have reduced levels of FT4, both of which are indicative of an underactive thyroid. Several scientific studies indicate that TSH concentration is likely to be age dependent. In the Whickham survey, the incidence of elevated TSH levels is approximately 7.6 per cent in the general female population. However, in women over the age of 70 this rises to 17 per cent.


The incidence of hyperthyroidism, according to the Wickham survey, is highest among females aged 18-24. However, the symptoms of an overactive thyroid can be mistaken for those of the menopause like anxiety, hot flushes, heart palpitations and insomnia.

Our results show that the demographic with the highest proportion of low TSH levels are in women aged between 60 and 69. Plus, 4.97 per cent of postmenopausal women have suppressed blood TSH levels.

How much do thyroid issues cost the NHS?

  • The cost of thyroid prescriptions has fallen by £2,921,616 between April 2015 and April 2019.
  • The number of prescriptions in the same 4-year period has risen by 5006.
  • Levothyroxine and Eltroxin (brand name for levothyroxine) are prescribed most in London, with the North East having the lowest number of prescriptions.
  • Levothyroxine is the third most prescribed drug in the United Kingdom.

There are two forms of levothyroxine included in this data, levothyroxine and Eltroxin. Eltroxin is a branded version whereas levothyroxine is the generic form. Generally, branded drugs are more expensive than generic forms. The NHS is more likely to use the generic version because they contain the same active ingredients. So, they work just as effectively but cost far less.

Levothyroxine and Eltroxin are prescribed for an underactive thyroid. Levothyroxine has been the standard treatment for this thyroid condition for decades.

The thyroid and doctor Google

According to Google trends data, the UK population is very much aware of thyroid problems and are keen to learn more.

  • In March, April, May and June 2019 the term ‘overactive thyroid’ was searched on average 33,200 times. This was the greatest number of times the term was searched, compared to February 2018 when the average number of searches totalled 14,800.
  • The trends data for the term ‘underactive thyroid’ was even greater. In March and May 2019, the average number of times it was searched was 74,000. In April and June of the same year it was 60,500.
  • ‘Underactive thyroid symptoms’ was searched an average of 33,200 times during the months of May and June 2019.
  • ‘Overactive thyroid symptoms’ was searched an average of 14,800 times during May and June 2019.
  • Average searches for ‘thyroxine’ are lower and peak at 14,800 in May 2019.

What is the thyroid gland?

With the appearance in shape resembling that of a butterfly, the thyroid gland is positioned in the neck between the two collar bones and in front of the windpipe. Its most important function is producing hormones that aid in regulating the body’s metabolism.

The thyroid is responsible for producing two hormones, thyroxine (T4) and triiodothyronine (T3). In the cells of the body, T4 is converted into T3. T3 is the biologically active hormone and influences the activity of all the cells in the body.

T3, whether derived from T4 or released straight from the thyroid, T3 regulates the speed at which your cells work, this is your metabolism. If too much of the hormones are secreted, then the cells work faster than normal and if too little is secreted, they work slower than normal. If your cells work either too fast or too slow, this can have a direct impact on your health.

What is an underactive thyroid?

An underactive thyroid is also known as hypothyroidism. It is caused by the thyroid gland not producing enough thyroxine for the body’s needs. Hypothyroidism results in the body’s cells and tissues working slower than normal. As a result, the intestines work slowly and can cause constipation.

The condition causes symptoms like:

  • Tiredness
  • Weight gain
  • Poor concentration
  • Feeling cold
  • Depression

Hypothyroidism is the most common thyroid disorder.

What is an overactive thyroid?

An overactive thyroid is also known as hyperthyroidism. It is caused by too much of the thyroid hormones being released by the thyroid. So, the cells in the body work faster and can lead to a faster heartbeat and frequent bowel motions or diarrhoea because the organs work faster.

The condition causes symptoms like:

  • Weight loss
  • Anxiety
  • Sore eyes
  • Changes in mood
  • Heat intolerance

Ways to improve thyroid function

Both diet and exercise can improve the function of the thyroid. Eating a diet that includes a good source of protein coupled with aerobic exercise will give the thyroid a boost in performing its duties.


Eating a healthy, balanced diet is key for any thyroid condition. Individuals with an underactive thyroid often experience constipation. So, it is vital that they increase their fibre intake to aid the function of their digestive system.

Emphasis should be placed on eating:

  • Lean meat
  • Fruit
  • Vegetables
  • Wholegrains
  • Fish

There is no specific diet for an overactive or underactive thyroid. However, nutrient deficiencies or excesses can make symptoms worse. Therefore, it is important to seek advice from a medical or nutritional professional before supplementing your diet.


In individuals with an underactive thyroid, exercise has been shown to improve thyroid function. For example, moderate-intensity exercise can reduce TSH levels and increase T3 and T4. Exercise is also great for weight loss which is a side effect of an underactive thyroid.


Cigarette smoking has been shown to reduce thyroid function. Some studies have found smoking is associated with reduced TSH levels. Plus, if you have an overactive thyroid and you smoke, you are at a greater risk of developing thyroid eye disease, which in the most severe cases can cause blindness.


The key findings in summary:

  • Women are more likely to experience thyroid issues.
  • 1 in 50 women in the UK live with an overactive thyroid condition.
  • Women are 6 times more likely to have a overactive thyroid problem than men.
  • Our data shows 25.91% of women aged between 50 and 69 had high TSH levels.
  • The risk of developing a thyroid issue increases with age.
  • Hypothyroidism is common in postmenopausal women. Our data shows 13.26 per cent of post-menopausal women have increased TSH levels and 6.78 per cent have reduced levels of FT4.
  • On average in 2019, there were between 60,500 and 74,000 searches per month for an ‘underactive thyroid’.
  • In one month alone (April 2019), there were 32,185 prescriptions for levothyroxine at a cost of £4,942,451.
  • The cost of levothyroxine prescriptions to the NHS has fallen since 2015 but the number of prescriptions has increased.

The data collected represents individuals who are now aware they have a thyroid issue. However, there is a proportion of individuals who may be unaware they have a thyroid problem or maybe associating the symptoms with other conditions like the menopause. Women are more likely to experience a thyroid problem. Therefore, it is essential to have a thyroid check to ascertain your own levels.

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- Health scores calculated


Article references

  1. Bansal, A et al. (2015). The Effect of Regular Physical Exercise on the Thyroid Function of Treated Hypothyroid Patients: An Interventional Study at a Tertiary Care Center in Bastar Region of India. AMHS: 3(2), pp 244-246.

  2. Gietka-Czernel, M. (2017). The Thyroid Gland in Postmenopausal women: Physiology and Diseases. Prz Menopauzalny: 16(2), pp 33-37.

  3. Ingoe, L et al. (2017). Prevalence of Treated Hypothyroidism in the Community: Analysis from General Practices in North-East England with Implications for the United Kingdom. Clinical Endocrinology: 87(6).

  4. Kim, S, J et al. (2019). Impact of Smoking on Thyroid Gland: Dose-Related Effect of Urinary Cotinine Levels on Thyroid Function and Thyroid Autoimmunity. Scientific Reports: 9.

  5. Werhun, A and Hamilton, W. (2013). Are We Overusing Thyroid Function Tests? Br J Gen Pract: 63(613).

This article was written by Forth

This information has been medically reviewed by Dr Thom Phillips

Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.

Dr Thom Phillips

Dr Thom Phillips

Head of Clinical Services