Thyroid storm, also known as thyrotoxic crisis, is an acute, life-threatening complication of hyperthyroidism. It is an exaggerated presentation of thyrotoxicosis. It comes with sudden multisystem involvement. The mortality associated with thyroid storm is estimated to be 8-25% despite modern advancements in its treatment and supportive measures. Thus, it is very important to recognize it early and start aggressive treatment to reduce mortality.
The diagnosis of thyroid storm is clinical.
Superimposed precipitating factors cause thyroid storm in patients with diagnosed or undiagnosed hyperthyroidism. It is more common with Graves’ disease but can occur with other etiologies of hyperthyroidism, for example, toxic multinodular goiter and toxic adenoma of the thyroid.
The precipitating factors are:
It is a rare presentation of hyperthyroidism. Thyroid storm accounts for about 1% to 2% of admissions for hyperthyroidism. As per the United States survey, the incidence of storm ranged from 0.57 t0 0.76 cases per 100,000 per year in the normal population, and 4.8 to 5.6 cases/100,000 per year in hospitalized patients. As per the Japanese National Survey, the incidence of thyroid storm was 0.2 per 100,000 population per year, about 0.22% of all thyrotoxicosis patients and 5.4% of hospitalized thyrotoxicosis patients. The average age of people with thyroid storm was 42 to 43 years, which was similar to people with thyrotoxicosis without thyroid storm. The male to female ratio for the incidence of thyroid storm was about 1:3, similar to thyrotoxicosis without storm group.
The pathophysiological basis for precipitation of thyroid storm in patients with thyrotoxicosis is not clear. But, a precipitating factor, as mentioned above, is always required to cause thyroid storm. Several hypotheses have been purposed. One hypothesis suggests the incidence of thyroid storm is due to the rapid increase in thyroid hormone levels, rather than the absolute hormone level that occurs during thyroid surgery, following radioactive iodine treatment, after sudden discontinuation of the antithyroid drug, or after administration of the large dose of iodine in contrast studies. The hyperactivity of the sympathetic nervous system with increased response to catecholamine along with an increased cellular response to thyroid hormone during acute stress or infections, causing cytokines release and altered immunological disturbances, are other possible mechanisms of thyroid storm. Most studies have failed to relate higher thyroid hormone levels as a cause of thyroid storm, except for the study by Brooks and others, reported higher free thyroid hormone among the patients with thyroid storm. In other words, the degree of thyroid hormone level is not directly related to a higher incidence of thyroid storm.
The clinical features are due to the exaggerated effects of the thyroid hormone. There is intense metabolic activity which increases oxygen requirements. The resulting tachycardia to meet the oxygen requirements can induce heart failure and predisposes the patient to arrhythmias. Similarly, the CNS symptoms include irritability, seizures, delirium, and eventually coma.
Histopathology depends on the cause of the thyroid storm. The most common cause Grave's disease shows diffuse follicular hyperplasia along with increased thyroid receptor antibodies and increased vascularization to the tissue. If it is a tumor causing storm, malignant cells infiltrate and destroy the thyroid tissue freely, and rupture the follicles.
Toxicokinetics are the precipitating factors:
Presentation of thyroid storm is an exaggerated manifestation of hyperthyroidism, with the presence of an acute precipitating factor. Fever, cardiovascular involvement (including tachycardia, heart failure, arrhythmia), central nervous system (CNS) manifestations, and gastrointestinal symptoms are common. Fever of 104 F to 106 F with diaphoresis is a key presenting feature. Cardiovascular manifestations include tachycardia more than 140 HR/minute, heart failure with pulmonary edema and peripheral edema, hypotension, arrhythmia, and death from cardiac arrest. CNS involvement includes agitation, delirium, anxiety, psychosis, or coma. Gastrointestinal (GI) symptoms include nausea, vomiting, diarrhea, abdominal pain, intestinal obstruction, and acute hepatic failure. A Japanese study found the CNS involvement to be a poor prognostic factor for increased mortality.
Physical examination findings may include high temperature, tachycardia, orbitopathy, goiter, hand tremors, moist and warm skin, hyperreflexia, systolic hypertension, and jaundice.
The diagnosis of thyroid storm needs clinical suspicion based on the presentation mentioned above in a patient with hyperthyroidism or suspected hyperthyroidism. One should not wait for lab results before starting treatment. Thyroid function tests can be obtained which usually show high FT4/FT3 and low TSH. It is not necessary to have a very high level of thyroid hormone to cause thyroid storm. Other lab abnormalities may include hypercalcemia, hyperglycemia (due to inhibition of insulin release and increased glycogenolysis), abnormal LFTs, high or low white blood cell (WBC) count.
In 1993, the following scoring system for the diagnosis of thyroid storm was introduced:
Diagnosis: A total score of more than 45 is highly suggestive of thyroid storm, 25 to 44 supports the diagnosis, and less than 25 makes the diagnosis unlikely.
The Japanese Thyroid Association (JTA)
This is a different scoring system based on similar clinical findings. Thyrotoxicosis (elevated FT3 and/or FT4) is a prerequisite, and it requires various combinations of following symptoms:
Definite Thyroid Storm (TS1): Thyrotoxicosis (elevated FT3 and/or FT4) plus
Suspected Thyroid Storm (TS2): Thyrotoxicosis (elevated FT3 and/or FT4) plus
These scoring systems are just guidelines. The actual diagnosis is based on clinical judgment. Based on the BWPS scoring system, a score of 45 or more is more sensitive but less specific than JTA scoring systems TS1 or TS2 to detect thyroid storm cases. BWPS score of 25 to 45 may suggest an impending storm.
A chest x-ray may be done to assess heart failure. Head CT may help exclude a neurological cause in some patients.
An ECG is often done to monitor for arrhythmias.
Treatment of thyroid storm consists of supportive measures like intravenous (IV) fluids, oxygen, cooling blankets, acetaminophen, as well as specific measures to treat hyperthyroidism. If any precipitating factors, for example, infection, are present, that needs to be taken care of. Patients with thyroid storm must be admitted to the intensive care unit with close cardiac monitoring and ventilatory support if needed.
Specific Strategic Steps for Treatment
After initial supportive measures, a beta-blocker should be started for any case of suspected thyroid storm. Typically, propranolol 40 mg to 80 mg is given every 4 to 6 hours. Then, either a loading dose of propylthiouracil (PTU) 500 mg to 1000 mg followed by 250 mg every 4 hours or Methimazole (MMI) 20 mg every 4 to 6 hours should be given. Propylthiouracil is favored because it has a small but additional effect of blocking the peripheral conversion of T4 to T3. An hour after the administration of propylthiouracil or Methimazole, give five drops of SSKI (supersaturated potassium iodide) by mouth every 6 hours. Always administer thionamide before starting iodine solution (SSKI) therapy.  This prevents the imminent increase in thyroid hormone synthesis due to increased iodine load from super saturated potassium iodide. Hydrocortisone 100 mg IV every eight hours (or Dexamethasone 2 mg every 6 hours) should also be started. If available, oral cholestyramine 4 grams four times daily can be started for severe cases. One should look for precipitating factors and treat them accordingly. The use of aspirin should be avoided due to its potential risk of increasing free thyroid hormone levels by interfering with thyroid binding protein.
In the first 24 hours of treatment, propylthiouracil decreases T3 level by 45%, but Methimazole drops T3 level by only 10 % to 15%. Methimazole, whereas, causes more rapid normalization of serum T3 level after a few weeks of treatment and it has less hepatotoxicity compared to propylthiouracil. Therefore, after initial stabilization, we should treat with Methimazole (if propylthiouracil was started at the beginning, it should be changed to Methimazole). For patients who cannot take oral antithyroid medicine, liquid preparation (pharmacist may have to compound) can be given as enemas. Sometimes, pharmacists can prepare an IV form of antithyroid medicine by dissolving the tablet.
Esmolol, a short-acting beta-blocker, at a loading dose of 250 mcg/kg to 500 mcg/kg followed by 50 mcg/kg to -100 mcg/kg/minute can be given in ICU setting. For patients with reactive airway disease, cardioselective beta-blockers like atenolol or metoprolol should be chosen. If there is a contraindication for the use of beta-blockers, diltiazem is an alternative.
If thionamide therapy is contraindicated because of an allergic reaction, thyroidectomy is needed after treatment with a beta-blocker, hydrocortisone, cholestyramine, and iodine solution. Plasmapheresis is the last resort if all other measures fail.
Once patients’ clinical conditions improve, the iodine solution should be stopped, glucocorticoids can be tapered and stop, and beta-blocker should be adjusted. Thionamide therapy should be titrated, and if propylthiouracil is used initially, it should be switched to Methimazole. Patients should be recommended for definitive treatment with radioiodine (RAI) therapy or thyroidectomy.
Surgery may be required in patients with grave's disease for the treatment of hyperthyroidism. These patients need to be pretreated with beta-blockers, glucocorticoids, and iodine formulas. Surgery is usually done after 5-7 days.
Thyroid storm should be differentiated from other diseases of similar symptoms and signs. As fever is the most common presentation of multiple diseases, so it can be misdiagnosed. The differential diagnosis are:
If toxic adenoma or multinodular goiter is causing this disease, then surgical resection and radioactive iodine ablation are the mainstay of treatment. Thyroidectomy is preferred if a patient has compressive symptoms. Patients who refuse ablation or have contraindications to surgery can be treated with long-term antithyroid medicines.
Grave's disease with intrathoracic mass causes severe compressive symptoms and thyroidectomy is preferred in these cases. Thyroidectomy has other adverse effects like recurrent laryngeal nerve damage and hypoparathyroidism.
Radioiodine-131 (I) therapy is helpful in hyperfunctioning nodules. But the risk of hypothyroidism is 60% after a 20 year follow up in a study of I in hyperthyroidism. Other factors increasing the risk of hypothyroidism in these patients are:
Randomized trials are still under process for efficacies and safety of more medicines. 
Complete surgical resection of thyroid and radioiodine ablation can cause hypothyroidism. So these patients need lifetime exogenous thyroxine therapy and should be monitored for hyperthyroidism. Dose adjustments by endocrinologists are crucial as the patient is at the risk of both hypothyroidism and hyperthyroidism.
Antithyroid drugs, MMI and PTU, causes agranulocytosis. Patients on these drugs should be monitored with CBCs especially white cell count. If white cell count starts decreasing, these drugs should be discontinued due to the increased risk of infection.
Thyroid storm is a real medical emergency which is fatal if left untreated. Cause of death may be heart failure, arrhythmias or multiple organ failure. However, with treatment, most patients see an improvement within 24 hours. Risk factors for poor prognosis include:
If left untreated, thyroid storm can lead to the following complications:
Patients with hyperthyroidism should be educated about the warning symptoms of thyroid storm, a serious but fortunately a rare emergency. As it is a dreadful disease but early diagnosis and prompt treatment can improve the condition. It should be discouraged to delay visiting emergency after experiencing any one of the symptoms. After the first crisis, non-compliant behaviors should be addressed and treatment benefits and complications should be described. 
There are multiple factors responsible for delayed diagnosis and treatment of this emergency condition:
Thyroid storm is a rare life-threatening medical emergency that is difficult to diagnose. Thus, an interprofessional team that includes an intensivist, cardiologist, endocrinologist, internist, emergency department physician, and infectious disease expert is recommended. These patients are best managed in the ICU and monitored by ICU nurses. Nurses need to be fully aware of the potential complications and notify the physician if there is any change in the hemodynamic status.
Treatment of thyroid storm consists of supportive measures like intravenous (IV) fluids, oxygen, cooling blankets, acetaminophen, as well as specific measures to treat hyperthyroidism. If any precipitating factors, for example, infection, are present, that needs to be taken care of first. Patients with thyroid storm must be admitted to the intensive care unit with close cardiac monitoring and ventilatory support if needed.
The pharmacist may need to prepare a special formula of iodine that can be administered intravenously. The use of radiocontrast dyes may help in some patients. In some cases, plasmapheresis may be life-saving. The nephrologist/hematologist must be involved early in the care of these patients and anticipate the need for plasmapheresis. The team must communicate with each other to avoid the high mortality of thyroid storm.
The outlook for patients with thyroid storm is guarded and depends on patient age, number of organs involved, comorbidity, need for mechanical ventilation, renal failure, and response to treatment.
|||2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis., Ross DS,Burch HB,Cooper DS,Greenlee MC,Laurberg P,Maia AL,Rivkees SA,Samuels M,Sosa JA,Stan MN,Walter MA,, Thyroid : official journal of the American Thyroid Association, 2016 Oct [PubMed PMID: 27521067]|
|||Life-threatening thyrotoxicosis. Thyroid storm., Burch HB,Wartofsky L,, Endocrinology and metabolism clinics of North America, 1993 Jun [PubMed PMID: 8325286]|
|||Galindo RJ,Hurtado CR,Pasquel FJ,García Tome R,Peng L,Umpierrez GE, National Trends in Incidence, Mortality, and Clinical Outcomes of Patients Hospitalized for Thyrotoxicosis With and Without Thyroid Storm in the United States, 2004-2013. Thyroid : official journal of the American Thyroid Association. 2019 Jan; [PubMed PMID: 30382003]|
|||Diagnostic criteria, clinical features, and incidence of thyroid storm based on nationwide surveys., Akamizu T,Satoh T,Isozaki O,Suzuki A,Wakino S,Iburi T,Tsuboi K,Monden T,Kouki T,Otani H,Teramukai S,Uehara R,Nakamura Y,Nagai M,Mori M,, Thyroid : official journal of the American Thyroid Association, 2012 Jul [PubMed PMID: 22690898]|
|||Free thyroxine concentrations in thyroid storm., Brooks MH,Waldstein SS,, Annals of internal medicine, 1980 Nov [PubMed PMID: 7212477]|
|||De Ridder M,Sermeus AB,Urbain D,Storme GA, Metastases to the thyroid gland-a report of six cases. European journal of internal medicine. 2003 Oct [PubMed PMID: 14769497]|
|||Shimaoka K,VanHerle AJ,Dindogru A, Thyrotoxicosis secondary to involvement of the thyroid with malignant lymphoma. The Journal of clinical endocrinology and metabolism. 1976 Jul [PubMed PMID: 59731]|
|||Clinical features and hospital outcomes in thyroid storm: a retrospective cohort study., Angell TE,Lechner MG,Nguyen CT,Salvato VL,Nicoloff JT,LoPresti JS,, The Journal of clinical endocrinology and metabolism, 2015 Feb [PubMed PMID: 25343237]|
|||Thyroid emergencies., Sarlis NJ,Gourgiotis L,, Reviews in endocrine & metabolic disorders, 2003 May [PubMed PMID: 12766540]|
|||Neiva J,Fernandes G,Carvalho D,Ferreira B,Duarte R,Araújo R, Thyroid storm and myxoedema: two reversible causes of acute heart failure. Acute medicine. 2018; [PubMed PMID: 30882107]|
|||Goodier CG, Endocrine Emergencies in Obstetrics. Clinical obstetrics and gynecology. 2019 Mar 13; [PubMed PMID: 30882392]|
|||Jacobi J, Management of Endocrine Emergencies in the ICU. Journal of pharmacy practice. 2019 Mar 10; [PubMed PMID: 30852927]|
|||Ba JH,Wu BQ,Wang YH,Shi YF, Therapeutic plasma exchange and continuous renal replacement therapy for severe hyperthyroidism and multi-organ failure: A case report. World journal of clinical cases. 2019 Feb 26; [PubMed PMID: 30842962]|
|||Kalpakam H,Dhooria S,Agarwal R,Mukherjee S,Sehgal IS, A rare complication of bedside tracheotomy: Thyroid crisis. Lung India : official organ of Indian Chest Society. 2019 Jan-Feb; [PubMed PMID: 30604713]|
|||Andrade Luz I,Pereira T,Catorze N, Thyroid storm: a case of haemodynamic failure promptly reversed by aggressive medical therapy with antithyroid agents and steroid pulse. BMJ case reports. 2018 Dec 14; [PubMed PMID: 30567262]|
|||Idrose AM, Acute and emergency care for thyrotoxicosis and thyroid storm. Acute medicine [PubMed PMID: 29123713]|
|||Vidal-Trecan GM,Stahl JE,Eckman MH, Radioiodine or surgery for toxic thyroid adenoma: dissecting an important decision. A cost-effectiveness analysis. Thyroid : official journal of the American Thyroid Association. 2004 Nov [PubMed PMID: 15671772]|
|||[PubMed PMID: 21154775]|
|||Watt T,Cramon P,Bjorner JB,Bonnema SJ,Feldt-Rasmussen U,Gluud C,Gram J,Hansen JL,Hegedüs L,Knudsen N,Bach-Mortensen P,Nolsøe R,Nygaard B,Pociot F,Skoog M,Winkel P,Rasmussen AK, Selenium supplementation for patients with Graves' hyperthyroidism (the GRASS trial): study protocol for a randomized controlled trial. Trials. 2013 Apr 30 [PubMed PMID: 23782950]|
|||Ceccarelli C,Bencivelli W,Vitti P,Grasso L,Pinchera A, Outcome of radioiodine-131 therapy in hyperfunctioning thyroid nodules: a 20 years' retrospective study. Clinical endocrinology. 2005 Mar [PubMed PMID: 15730415]|
|||Bartalena L, Diagnosis and management of Graves disease: a global overview. Nature reviews. Endocrinology. 2013 Dec [PubMed PMID: 24126481]|
|||[PubMed PMID: 27609732]|
|||Nakamura H,Noh JY,Itoh K,Fukata S,Miyauchi A,Hamada N, Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves' disease. The Journal of clinical endocrinology and metabolism. 2007 Jun [PubMed PMID: 17389704]|
|||Wang MT,Lee WJ,Huang TY,Chu CL,Hsieh CH, Antithyroid drug-related hepatotoxicity in hyperthyroidism patients: a population-based cohort study. British journal of clinical pharmacology. 2014 Sep [PubMed PMID: 25279406]|
|||Min T,Benjamin S,Cozma L, Thromboembolic complications of thyroid storm. Endocrinology, diabetes & metabolism case reports. 2014 [PubMed PMID: 24683480]|
|||[PubMed PMID: 28939923]|
|||Wyble AJ,Moore SC,Yates SG, Weathering the storm: A case of thyroid storm refractory to conventional treatment benefiting from therapeutic plasma exchange. Journal of clinical apheresis. 2018 Dec; [PubMed PMID: 30321468]|
|||Simsir IY,Ozdemir M,Duman S,Erdogan M,Donmez A,Ozgen AG, Therapeutic plasmapheresis in thyrotoxic patients. Endocrine. 2018 Oct; [PubMed PMID: 29968224]|