Thyroid disease at work | Insight


The thyroid is a small gland which sits in front of the windpipe at the base of the neck. It is responsible for producing the hormone thyroxine, which controls our metabolic rate.

Malfunctioning of the thyroid gland can either lead to too much or too little thyroxine being produced, both of which can affect wellbeing and our ability to function effectively in day-to-day life.

Underactive thyroid is also known as hypothyroidism, while overactive thyroid is known as hyperthyroidism.

Key takeaways

  • Underactive thyroid gland (hypothyroidism) affects approximately 2-3% of the UK population, and is at least five times more likely to occur in women than men
  • The most-common cause of underactive thyroid is an autoimmune disease in which the body’s immune system destroys the gland
  • Underactive thyroid causes a drop in hormone production and a slowing down of the metabolic rate, making a person feel lethargic and sluggish
  • Having an underactive thyroid gland also increases the risk of heart disease and raised cholesterol, if left untreated
  • Untreated hypothyroidism can affect the ability to perform optimally at work due to tiredness, however once adequately treated it should not impact function
  • Overactive thyroid gland (hyperthyroidism) affects 0.75% of the population, and is approximately 10 times more common in women than men
  • Increased production of thyroxine causes many symptoms, including a raised heart rate, increased appetite and weight loss
  • Equality legislation is likely to apply to these conditions

Symptoms and causes

An underactive thyroid will cause a person to feel extremely tired and fatigued, despite adequate rest. They may also suffer from weight gain, reduced appetite and hair loss. It can also make someone feel very cold regardless of the temperature outside.

Hyperthyroidism causes the body’s metabolic rate to increase. This can cause the heart to beat faster and some patients also develop an abnormal heart rhythm. Other symptoms include weight loss, feeling hungry more often, diarrhoea and feeling hot.

Grave’s disease — an autoimmune disease in which the body’s immune system stimulates the thyroid gland — is the most-common cause of hyperthyroidism.

With Grave’s disease, sufferers may notice a lump in their neck and that their eyes protrude forward.

If either hypothyroidism or hyperthyroidism are suspected, individuals should arrange a blood test via their GP.


Once a diagnosis of underactive thyroid is confirmed, the GP will initiate a tablet called levothyroxine to be taken daily. This increases the level of thyroxine hormone in the body, and sufferers will need to be on thyroxine replacement for life.

They will need regular blood tests to adjust the dose, to ensure it is within the normal range. If the level of thyroxine is high, as with hyperthyroidism, patients will be referred to an endocrinologist for treatment.

There are many different treatment options available. These include medication, radioiodine and surgery. Many people, after treatment for an overactive thyroid, go on to need long term thyroid replacement treatment.

Thyroid disease and work

Both overactive and underactive thyroid conditions can impact on work performance and attendance — and both can take some time to be diagnosed.

Prior to diagnosis, employees may experience the following issues:

Hypothyroidism Hyperthyroidism
  • Lack of motivation
  • Difficulty focusing
  • Struggle to meet deadlines
  • Anxiety
  • Poor memory
  • Upset stomach
  • Impaired concentration
  • Feeling hot / excessive sweating

While medical investigation is under way and when treatment is starting, they will require time off for medical appointments.

But in the medium term, once treatment is under way, impact on work should be minimal in most cases. Some treatments, such as radioiodine and surgery, might require additional time off work.

Occupational health can provide bespoke specialist advice to support an employee’s return to work, if needed.

Useful resources

NHS: Hypothyroidism

NHS: Hyperthyroidism

British Thyroid Foundation

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