Introduction

The thyroid is a small hormone-releasing gland in the neck that controls the body’s metabolism, and when it goes into overdrive, it can cause problems. One of the most common causes of an overactive thyroid is Graves’ disease, a disorder in which the immune system stimulates the thyroid excessively. If the condition is left untreated, there is a chance that Graves’ disease can trigger a thyroid storm, a dangerous and potentially life-threatening condition.

This article will explain what Graves’ disease is, how the condition affects the thyroid gland, and how, in severe cases, it can worsen and trigger a thyroid storm.

Graves’ disease: an autoimmune disease

What is Graves' disease?

Graves’ disease is an autoimmune condition mainly affecting the thyroid, a small butterfly-shaped gland in the neck that produces thyroid hormones. These hormones affect many organs in the body, and control things such as:¹

• Heart rate
• Mood
• Body temperature
• How quickly the body uses up energy from food (metabolism)

When you have Graves’ disease, your immune system releases an antibody known as thyroid-stimulating immunoglobulin (TSI), which activates the thyroid gland and causes it to make too much thyroid hormone. When there is excess thyroid hormones circulating in the blood, you develop a condition called hyperthyroidism, which can cause uncomfortable and potentially dangerous symptoms that can worsen without treatment. Graves’ disease can also affect other organs, including the eyes, skin and the liver.²

Symptoms

Most of the symptoms that are common in individuals with Graves’ disease are related to the overactivity of the thyroid (hyperthyroidism), and can include:³

• Low mood and irritability
• Losing weight despite an increased appetite and eating more
• Tierdness 
• Irregular menstrual periods
• Trouble sleeping (insomnia)
• Diarrhoea 
• Erectile dysfunction

Around 25% of people with Graves’ disease may also develop thyroid eye disease or Graves’ ophthalmopathy. Symptoms might include:³

• Bulging eyes: commonly seen in individuals with Graves’ ophthalmopathy. They are caused by the inflammation and growth of the tissue and muscles around the eyes
• Blurriness or loss of vision
• Red and inflamed eyes

In rarer cases, Graves’ disease can cause the build-up of protein in the skin, leading to darkening and thickening of the skin. This is known as Graves’ dermopathy, and leads to an orange peel-like skin texture on the shins and feet.

Causes and risk factors

Currently, it is not completely known why people develop Graves' disease, though certain conditions can make it more likely for someone to develop the disease. Some factors include:³

• Smoking
• Emotional stress
• Pregnancy (mostly postpartum)
• Infections
• Being female assigned at birth

Diagnosis

For most individuals, Graves’ disease is diagnosed after they present with classic symptoms such as unexplained weight loss, bulging eyes, and heat intolerance. Studies have shown that in younger people, their symptoms tend to be more severe than in older individuals. To confirm and diagnose someone with Graves’ disease, doctors will usually perform some tests, mostly to look at the levels of thyroid hormones.⁴

Blood tests 

Blood tests are typically performed to measure the levels of thyroid hormones in the body, which tend to be elevated in people diagnosed with Graves’ disease. Doctors may also test thyroid-stimulating hormone (TSH) concurrently, which is produced by the pituitary gland located in the brain. TSH serves as a hormone that stimulates the thyroid, and its levels are generally lower than average in those with this condition.

Another test that doctors might conduct is to detect levels of antibodies known to cause Graves’ disease. If no antibodies are detected, medical professionals might consider another cause of the hyperthyroidism.³

Radioactive iodine uptake

The body needs iodine to make thyroid hormones. To take advantage of this, doctors may give a small amount of radioactive iodine to an individual before scanning them with a special camera to see how much iodine gets taken up into the thyroid. If the iodine is taken into the thyroid very quickly, this may be another sign of Graves’ disease.³

Thyroid storm

What is a thyroid storm?

A thyroid storm, also called a thyrotoxic crisis, is a very rare but dangerous and life-threatening condition which happens when the body produces extremely high amounts of thyroid hormones. Typically, thyroid storm happens in those with either unmanaged or inadequately managed hyperthyroidism. This is especially common among individuals with Graves’ disease, as this condition complicates the regulation of thyroid hormone levels.^4,5

Symptoms

The symptoms of thyroid storm are usually similar or identical to those found in patients with Graves’ disease and hyperthyroidism, though they may be more severe. Symptoms can include:⁵

• Rapid heart rate
• High body temperature with sweating and fever
• Severe confusion and agitation
• Losing consciousness

If left untreated, thyroid storm can lead to seizures, comas and even heart failure.

The role of autoimmune hyperthyroidism in thyroid storm

While Graves’ disease does not directly lead to the onset of thyroid storm, the condition can play a major role in causing the thyroid to become overactivated. Whilst the effects of Graves’ disease mainly impact the thyroid, studies have also shown that the condition can increase overall inflammation throughout the body, leaving it more vulnerable to severe reactions and other effects.^6,7

Management and treatment of autoimmune-related thyroid storm

The recommended treatment options for thyroid storm involve a range of treatments, mainly aimed at controlling the activity of the thyroid and preventing the overproduction of thyroid hormone.

Radioiodine therapy

Radioiodine therapy is one of the first-line treatments for individuals with Graves’ disease, and involves the swallowing of a single dosage pill or liquid containing radioactive iodine. Since iodine is required by the thyroid for the production of thyroid hormones, the radioactive iodine is absorbed by the thyroid gland and eventually leads to destruction of the thyroid tissue over a few months.

Anti-thyroid medicines

Anti-thyroid medications such as methimazole and propylthiouracil (PTU) are also used to treat Graves’ disease. They work by preventing the thyroid gland from using iodine to make thyroid hormones. However, taking anti-thyroid medicines can also lead to increased chances of liver failure, making it a form of treatment used after radioiodine therapy as an additive treatment.⁸

Summary

Graves' disease is an autoimmune condition which can cause the overproduction of thyroid hormones. Insomnia, irritability, weight loss, and occasionally eye-related problems like Graves' ophthalmopathy are common symptoms. The risk of thyroid storm is a rare but potentially fatal illness marked by dangerously elevated thyroid hormone levels, fever, tachycardia, and extreme agitation, which can continue to worsen if Graves' disease is not treated. Usually, imaging methods using radioactive iodine uptake scans and blood tests to measure thyroid hormone and antibody levels are used to make the diagnosis. Radioiodine therapy, which gradually destroys thyroid tissue, and anti-thyroid drugs like propylthiouracil and methimazole, which stop the production of thyroid hormones, are available as treatment options.