What is thyroid storm?

Thyroid storms affect people with hyperthyroidism, and although rare,  can cause life-threatening conditions. It’s crucial to know and recognise the early symptoms to improve your chances of recovery.


What is a thyroid storm?

Thyroid storm is a flare up of the thyroid gland and occurs when your thyroid releases too much hormone over a short amount of time. Also known as thyrotoxic crisis, thyroid crisis, and thyrotoxicosis, thyroid storm is often due to a complication of untreated or serious hyperthyroidism.

In those living with hyperthyroidism, it’s estimated that around 8–25% of deaths are associated with thyroid storm, so it’s crucial to spot it early on and begin treatment to prevent escalation.1 

Thyroid Gland Function

T3 and T4

Your thyroid gland releases two main hormones – triiodothyronine (T3) and thyroxine. They control your body’s metabolism, turning food into energy.  

  • T3 is active; T3 helps with foetal skeletal development, such as acquiring and maintaining bone mass. T3 also contributes to the regulation of the nervous system resulting in increased attention and responsiveness.2
  • T4 is inactive and gets converted into T3 by an enzyme called iodothyronine deiodinase which is produced by your glial cells (located in the brain).2

T3 and T4 Regulation

Regulation of T3 and T4 is vital to normal function as it helps with endocrine systems such as the reproductive health of women and men. It does so by regulating the ovulation cycle and spermatogenesis.

Both T3 and T4 are controlled by a feedback loop system that involves  the hypothalamus, pituitary gland, thyroid gland, and various hormones.

Regulating T3 and T4 starts with the hypothalamus and the release of thyrotropin-releasing hormone (TRH). TRH is then released into the hypothalamic portal system and  taken to the anterior pituitary gland

How does this work?

  • TRH stimulates thyrotropin cells located in the anterior pituitary gland
  • Thyrotropin cells then release thyroid-stimulating hormone (TSH)
  • Once released into the bloodstream, TSH then binds to thyroid-releasing hormone (TSH-R)
  • TSH-R is important in the control of thyroid cell function and growth

Hyperthyroidism as a precursor to thyroid storm

Both hyperthyroidism and thyroid storm are caused by increased levels of thyroid hormone in your body,hence the two are interlinked. If you experience a thyroid storm, the symptoms of hyperthyroidism will be exaggerated.

Hyperthyroidism can be the precursor to thyroid storm if you are non-compliant with any prescribed thyroid medication or if you have been left untreated for a long period of time.4

Causes of thyroid storm

Underlying conditions

A thyroid storm can be triggered by a number of different reasons. 

Graves’ Disease

Graves’ Disease is an autoimmune disorder and the most common cause of hyperthyroidism.5 Graves’ disease occurs when the immune system produces an antibody called thyroid-stimulating immunoglobulin (TSI) that attaches to thyroid cells. TSI acts like TSH in that it causes the thyroid to produce too much hormone. 

Toxic Nodular Goitre 

Also known as Plummer Disease, toxic nodular goitre consists of enlarged areas of the thyroid gland which have formed one or more solid or cystic nodules. Following Graves’ disease, toxic-nodular goitre is thought to be the second most common cause of hyperthyroidism, and has been linked to thyroid storm.4

A thyroid storm can also be triggered by infection, surgery and stress.

Symptoms of a thyroid storm

The signs of a thyroid storm can include:5

  • Fever
  • Tremors
  • Psychosis or an increase in previous unusual behaviour
  • Confusion
  • Vomiting, which can cause dehydration
  • Increased agitation
  • Tachycardia

Some of the less obvious symptoms can include:

A hypermetabolic state, such as when your metabolism increases. This can be seen by an increased use of oxygen as well as other metabolic fuels such as glucose.6

There may also be cardiac concerns, such as arrhythmia presentations, ischemia and heart failure.7  

As well as cardiac concerns, there can also be gastrointestinal concerns, such as liver damage, diarrhoea, and abdominal pain.9


Clinical assessment

A clinical assessment is carried out by your GP, who will make a record of your symptoms, and if they indicate thyrotoxicosis then further tests will be conducted.

Tests may include:

  • Checking for TSH
  • T4 test
  • T3 test 
  • Testing for thyroid antibodies

Imaging studies

These tests include thyroid scans and ultrasounds and in some cases, radioactive uptake tests can be used.


Cardiovascular complications

In some rare cases, particularly in older patients, thyroid storm can be fatal, with cardiopulmonary failure being the most common cause of death.

If left untreated, then thyroid storm can cause individuals to fall into a coma..10

Neurological complications

It is possible for various neurological complications to arise from thyroid storm. Symptoms can be anything from emotional disorders to movement and higher-thinking function disorders.11

Treatment and management of Thyroid storm

Initial treatments of thyroid storm include supportive measures, such as providing intravenous fluids to help prevent dehydration, as well as treating the hyperthyroidism itself. Someone with thyroid storm will also be admitted to intensive care so they can receive cardiac monitoring and ventilation support if symptoms progress.11

After these supportive measures, then medication will be used. In these cases, the preferred medication is methimazole, which causes TSH levels to slow down. Due to potential links to liver failure, Propylthiouracil is given only in extreme cases, as it has been found to reduce T3 levels by up to 45%. If for any reason you cannot take oral antithyroid medication, liquid forms of the antithyroid medicine can be prepared by the pharmacists. A short-acting beta-blocker called Esmolol can be provided to those in intensive care.

As with all treatments, dosage is monitored and altered accordingly, depending on how the patient reacts.  For example it can identify whether someone is resistant to certain treatments and an alternative needs to be provided. 

With successful treatment,  you should see improvement within 24 hours, and be through the worst of it within a week, enabling you to recover as normal.

Those with Graves disease may require surgery, and will be  given beta-blockers, glucocorticoids and iodine, with surgery taking place after 5-7 days.12


Mortality rates as a result of thyroid storm is approximated around 8 to 25% hence making it very important that you can recognize it early and start treatment.12  A similar severe outcome is likely in children however this is not certain as of now.  

Long term implications following treatment are uncommon as thyroid hormones can reset to a normal level. A thyroid storm may leave you with temporary shock or weakness, but recovery is expected.

The risk factors for a poor outcome occur if your hyperthyroidism is left untreated or if you are not being compliant with thyroid medication.


You can prevent your chances of a thyroid storm by addressing and correctly treating the cause of your hyperthyroidism. It is also key to realise that there are other triggers to be aware of, including stress, infection, surgery and trauma. So, managing your stress, keeping healthy with exercise, and eating well all play a significant role in its prevention.

If you feel as though you or someone else have the relevant symptoms, you should seek immediate medical attention as early intervention can prevent further complications from thyrotoxicosis.


A thyroid storm is life-threatening if not treated early with the right treatment. It is often experienced by people with hyperthyroidism especially if it is uncontrolled or if symptoms are heightened due to other triggers.

Early recognition will allow your medical team to provide the appropriate treatments and manage any cardiovascular, neurological or gastrointestinal symptoms. This will soon help you feel better and bring your thyroid levels down to a normal level.

Although there have been many advancements in the treatment of thyrotoxicosis, more research is required.

Any information in this article is not meant to be or replace professional advice. Ensure you seek immediate medical guidance.


  1. Pokhrel B, Aiman W, Bhusal K. Thyroid storm. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Oct 6]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK448095/
  2. Armstrong M, Asuka E, Fingeret A. Physiology, thyroid function. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Oct 13]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK537039/
  3. Shahid MA, Ashraf MA, Sharma S. Physiology, thyroid hormone. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Oct 9]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK500006/
  4. Leung AM. Thyroid emergencies. J Infus Nurs [Internet]. 2016 [cited 2023 Oct 11];39(5):281–6. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657262/
  5. Pokhrel B, Bhusal K. Graves disease. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Oct 11]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK448195/
  6. Khalid N, Can AS. Plummer disease. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Oct 12]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK565856/
  7. De Groot LJ, Bartalena L, Feingold KR. Thyroid storm. In: Feingold KR, Anawalt B, Blackman MR, Boyce A, Chrousos G, Corpas E, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000 [cited 2023 Oct 12]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK278927/
  8. Carroll R, Matfin G. Endocrine and metabolic emergencies: thyroid storm. Ther Adv Endocrinol Metab [Internet]. 2010 Jun [cited 2023 Oct 13];1(3):139–45. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3475282/
  9. Waqar Z, Avula S, Shah J, Ali SS. Cardiovascular events in patients with thyroid storm. J Endocr Soc [Internet]. 2021 Mar 11 [cited 2023 Oct 13];5(6):bvab040. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143654/
  10. Nai Q, Ansari M, Pak S, Tian Y, Amzad-Hossain M, Zhang Y, et al. Cardiorespiratory failure in thyroid storm: case report and literature review. J Clin Med Res [Internet]. 2018 Apr [cited 2023 Oct 13];10(4):351–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5827921/
  11. Doherty C. Neurologic manifestations of thyroid disease. The Neurologist [Internet]. 2001 May [cited 2023 Oct 13];7(3):147. Available from: https://journals.lww.com/theneurologist/abstract/2001/05000/neurologic_manifestations_of_thyroid_disease.2.aspx#:~:text=BACKGROUND,rarer%20yet%20significant%20neurologic%20sequelae.
  12. Pokhrel B, Aiman W, Bhusal K. Thyroid storm. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Oct 13]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK448095/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Natasha Kaur

Biomedical Science – Bachelors of Science, University of Lincoln, UK

Natasha is a dedicated full-time student with a significant background in all things health and biology related, acquired over several years, which is why sharing concise health-related knowledge to the public has developed into one of her strong passions. Her interest lies in cancer-related topics, including her final year degree dissertation project, and so educating people about the disease is of particular interest to her. She has established recent experience in medical writing with Klarity Health which has pointed her into a full-time writing career, post graduating.

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