Introduction  

What is the thyroid? 

The thyroid is a butterfly-shaped gland located in the neck, in front of the windpipe.¹ Glands are tissues that release substances, such as the salivary glands, which produce saliva.² Unlike salivary glands, the thyroid does not release substances, but it releases hormones into the bloodstream, which travel to various organs and help regulate essential bodily processes.³

Image showing the location of the thyroid. (Photo Credit: BioRender)

The question is: How can such a small organ play such a crucial role in the body's function? To answer this, we must first explore how the thyroid works and the functions of the hormones it releases.

How does the thyroid work? 

The thyroid functions by absorbing iodine from the bloodstream and then using it to make thyroid hormones.³ These hormones include triiodothyronine (T3), the active form, and thyroxine (T4), the inactive form. The thyroid mostly produces T4, which can easily be transported through the bloodstream to reach various tissues and organs. Once it arrives at the target tissue, T4 is converted into T3, allowing the hormone to take effect.¹

Schematic diagram of the thyroid function. (Photo Credits: BioRender)

Why are thyroid hormones so important? 

Thyroid hormones play a crucial role in developing tissues and in keeping our internal environment stable by regulating specific responses in our tissues.¹ The following examples will show how thyroid hormones affect different parts of the body. 

Growth 

Thyroid hormones stimulate a process called endochondral ossification, which is essential for bone development. This process begins between the sixth and seventh week of embryonic development, starting with the formation of cartilage. It continues throughout the teenage years, during which the cartilage is gradually replaced by bone.^4,5 Endochondral ossification is crucial for the growth and development of the skeletal system, which provides the body with support, strength, and protection.

Metabolism

Thyroid hormones help various metabolic processes. Metabolism involves several chemical reactions that take place within a cell, which provide us with energy. This includes the breakdown of carbohydrates in a process known as cellular respiration. This breakdown helps provide energy to several processes, including growth, muscular contraction, and nerves to send signals.³ 

Heart 

Thyroid hormones support the movement of calcium ions into the heart muscle cells, which is essential for contractions to occur. Additionally, they cause blood vessels in the skin, muscles, and heart to dilate, helping to counteract the rise in blood pressure caused by increased heart contractions. ¹ 

What is a thyroid storm? 

It is evident that the thyroid plays a vital role in the body by regulating several important processes. Because of its significance, the activity of the thyroid is carefully controlled by hormones released from the hypothalamus and the pituitary gland in the brain.³ These hormones signal the thyroid when to produce and release its hormones. But what happens when the thyroid’s activity is not properly regulated?

When thyroid activity is not controlled, it can lead to a condition known as thyrotoxicosis or hyperthyroidism, which occurs when abnormally high levels of thyroid hormones circulate in the blood.⁶ This condition has been reported by the NHS to be more common in women and typically affects people between the ages of 20 and 40 years. While some individuals may experience no symptoms, others develop signs such as unintended weight loss, feelings of overheating, and noticeable or rapid heartbeats.⁶ 

If thyrotoxicosis is left untreated, it can progress to a life-threatening condition called thyroid storm. Prolonged overactivity of the thyroid can become fatal, leading to symptoms such as high fever, altered mental state, signs of heart failure and impaired liver function.⁶ These symptoms highlight why thyroid storms require immediate medical attention. To prevent life-threatening complications, it is important to understand the causes of thyroid storms and what warning signs to watch for. In this article, we will cover: 

• The symptoms typically experienced by patients with thyroid storm 
• The common triggers of thyroid storm 
• What actions should to take if you suspect someone is experiencing a thyroid storm

Symptoms of thyroid storm  

Thyroid storms can cause the following symptoms: 

• High fever: An overactive thyroid raises the metabolic rate of cells, increasing energy production. While most of this energy is used by the cells, a portion is lost as heat, causing a rise in body temperature⁷ 
• Altered mental state: High levels of T3 and T4 have been linked to psychosis with agitation, delusions and hallucinations⁸ 
• Signs of cardiac failure: During a thyroid storm, there is increased movement of calcium ions into heart muscle cells, which overstimulates the heart, causing an abnormally high heart rate. Prolonged overactivity can cause the heart to enlarge and weaken, reducing its ability to contract properly and potentially leading to heart failure⁹ 

Common triggers of thyroid storm  

Although thyroid function is carefully regulated by the hypothalamus and pituitary gland, certain factors can disrupt this control system. Graves’ disease and infections are the most common triggers, but other causes include iodine contrast dye, medications, and surgical procedures.¹⁰

Graves’ disease 

Graves’ disease is an autoimmune condition in which the immune system stimulates the thyroid gland, leading to excessive thyroid hormone production, causing thyrotoxicosis. If left untreated, this can worsen and potentially trigger a thyroid storm. Effective treatment of Graves’ disease is essential to managing the condition and reducing the risk of severe complications.

Infections

The exact mechanism by which infections trigger a thyroid storm is not fully understood, but a link has been established. The physical stress caused by a systemic infection (an infection that affects the entire body as it travels in the bloodstream) has been shown to increase thyroid activity, potentially leading to an increased production of T3 and T4.

Iodine exposure and contrast agents

CT scans provide detailed images by using contrast dyes such as iodine and barium. These dyes are safe for oral, rectal, or intravenous administration and are naturally eliminated from the body through urine. 

Iodine contrast dyes can lead to a temporary increase in iodine levels, which may reduce iodine transport in the thyroid, a phenomenon known as the acute Wolff-Chaikoff effect. In most cases, the thyroid adapts to this change, but if this regulatory mechanism fails, it can lead to thyroid disorders such as thyrotoxicosis, which in severe cases may trigger a thyroid storm.¹¹ 

Medications

Certain medications, such as amiodarone, can also trigger thyroid storms. Amiodarone is commonly prescribed for patients with abnormal heart rhythms, known as ventricular arrhythmias. However, due to its high iodine content, it can be harmful to individuals with pre-existing thyrotoxicosis as it increases the likelihood of heart failure. Due to this risk, patients taking amiodarone require careful monitoring to ensure thyroid function remains stable. Additionally, thyroid storms can be prevented through regular check-ups that include taking thyroid function tests to monitor hormone levels and detect any abnormalities early on.¹²

Surgical procedures

Although there is no clearly established link between surgical procedures and thyroid storms, it has generally been understood that surgery in patients with undiagnosed thyrotoxicosis or inadequate preparation before surgery can increase the risk.¹³ Recognising thyrotoxicosis beforehand allows doctors to take necessary precautions, such as administering barbiturates or benzodiazepines for sedation while avoiding anticholinergic drugs, which can interfere with the body's heat regulation and trigger tachycardia (fast heart rate).¹⁴

What actions should to take if you suspect someone is experiencing a thyroid storm?

As this is a medical emergency, the NHS recommends calling 999 and requesting an ambulance immediately if you suspect someone is experiencing a thyroid storm. Providing relevant medical information, such as a history of Graves’ disease or recent exposure to iodine contrast from a CT scan, can help guide immediate treatment. Identifying the underlying cause is crucial, as it significantly improves the chances of effective management and recovery.

Frequently asked questions

What is the mortality rate for someone with a thyroid storm? 

Norfolk and Norwich University Hospitals report a mortality rate of 20-30%, highlighting the severity of this condition. This makes it a medical emergency that requires prompt treatment.

What is the difference between thyrotoxicosis and thyroid storm? 

Thyrotoxicosis is characterised by elevated levels of T3 and T4 hormones in the blood. While thyrotoxicosis itself is not considered life-threatening, it can increase the risk of breast cancer.¹⁵ Furthermore, if left untreated, it may lead to a thyroid storm, which is a severe and potentially fatal condition. 

Why do people with thyroid issues wake up at 3 am? 

Elevated levels of thyroid hormones influence our sleep-wake cycle, known as the circadian clock. This shifts the clock forward, causing individuals with thyroid issues to wake up earlier than usual.¹⁶ 

Summary  

A thyroid storm is a life-threatening condition caused by excessive thyroid hormone activity, which disrupts body temperature, mental state, and the function of the heart and liver. Common triggers include Graves’ disease and infections, whilst other potential causes include iodine contrast dye, certain medications, and surgical procedures. Recognising these triggers early is essential for prompt treatment, which will help prevent serious complications.