What is hyperthyroidism?

Hyperthyroidism is a term that we frequently hear, but what does it mean?

The thyroid is a small butterfly-shaped gland that can be found at the front of the neck, just behind the windpipe. It distributes two essential hormones known as triiodothyronine (T3) and thyroxine (T4). These influence nearly all metabolic processes in the body, from how we turn food into energy, to how we regulate temperature.

Most of us have perfectly functioning thyroids, producing just the right quantity of these helpful hormones. In some, however, the thyroid can speed up, resulting in hyperthyroidism.

What is hyperthyroidism?

When the thyroid becomes ‘hyper’ it produces too much T3 and T4. Many of our bodily functions speed up, including metabolism and heart rate.

Symptoms of an overactive thyroid include:

  • Nervousness, anxiety and irritability
  • Restlessness, twitching or trembling
  • Insomnia
  • Diarrhoea
  • Needing to wee more often than usual
  • Persistent thirst
  • Itchiness
  • Excessive sweating
  • Sensitivity to heat
  • Heart palpitations
  • Weight-loss (despite an increased appetite)
  • Irregular or heavy periods

It’s worth noting that not all symptoms develop in all cases and the severity of symptoms can vary.

What causes hyperthyroidism?

An overactive thyroid can affect anyone, but it’s about 10 times more common in women than in men. It typically occurs between the age of 20 and 40.

Graves’ disease is the cause in the vast majority of cases (approximately 75%). This autoimmune condition triggers excess production of TSH (thyroid-stimulating hormone), which does exactly what it says on the tin. It stimulates the thyroid, encouraging it to release excessive amounts of T3 and T4. We don’t know what causes Graves’ disease, but it often runs in families and tends to affect young or middle-aged women. Research shows that smoking can also increase the risk of contracting Graves’ disease.

Though significantly less common, extra tissue growing on the thyroid (benign lumps) can also encourage the gland to become overactive. In contrast to Graves’, this most commonly affects those over 60.

Excess intake of iodine is another possible cause of hyperthyroidism. This is likely to be a result of taking medication that contains iodine, such as amiodarone (sometimes prescribed for an irregular heartbeat). It may also result from eating excessive amounts of seaweed, taking over-the-counter iodine supplements or even ill-advised ‘energy-boosting’ preparations that contain thyroid hormones.

What is the test for hyperthyroidism?

A simple blood test can determine whether we have hyperthyroidism. A GP will check levels of T3, T4 and TSH, and may also look out for the antibodies associated with Graves’ disease.

Guidelines state that following a diagnosis, patients should be referred to a specialist to establish the root cause of the issue and agree on a management plan.

Treatments for an overactive thyroid

There are three main treatments for hyperthyroidism:

  • Medication
  • Radiotherapy
  • Surgery

In most cases, a prescription of antithyroid medication will stop the thyroid producing so much T3 and T4. These drugs can act very quickly and patients recover in as little as two to three weeks. In the meantime, beta blockers may be prescribed for rapid symptom relief.

In rare cases (when medication is not tolerated), radiotherapy can be used to damage the thyroid and inhibit its ability to produce hormones.

Finally, removing part or all of the thyroid via surgery is another – albeit uncommon – method for suppressing hormone production.

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