Thyroid Storm

Thyroid storm, also known as thyrotoxic crisis, is an acute, life-threatening complication of hyperthyroidism.
It is an exaggerated presentation of thyrotoxicosis and is characterized by compromised organ function.
Whilst rare in the modern era, the mortality rate remains high (80% to 100% without treatment). Even with treatment, the mortality rate is between 10% and 50%.
Prompt consideration of this endocrine emergency, with specific treatments, can improve outcomes.

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:
Abrupt discontinuation of antithyroid medicine
Thyroid surgery
Non-thyroid surgery
Trauma
Acute illness like infections, diabetic ketoacidosis, acute myocardial infarction, cardiovascular accident, cardiac failure, drug reaction
Parturition
Recent use of Iodinated contrast medium
Radioiodine therapy (rare)
Burns
Stroke
Medication side effect e.g. amiodarone, anesthetics, salicylates.

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.

The diagnosis of thyroid storm needs clinical suspicion based on the presentation mentioned before 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.

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

Therapy to control increased adrenergic tone: Beta-blocker
Therapy to reduce thyroid hormone synthesis: Thionamide
Therapy to reduce the release of thyroid hormone: Iodine solution
Therapy to block peripheral conversion of T4 to T3: Iodinated radiocontrast agent, glucocorticoid, PTU, propranolol
Therapy to reduce enterohepatic recycling of thyroid hormone: Bile acid sequestrant


Reference:
Pokhrel B, Aiman W, Bhusal K. Thyroid Storm. [Updated 2020 Jul 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NB...
Carroll R, Matfin G. Endocrine and metabolic emergencies: thyroid storm. Ther Adv Endocrinol Metab. 2010;1(3):139-145. doi:10.1177/2042018810382481
Idrose AM. Acute and emergency care for thyrotoxicosis and thyroid storm. Acute Med Surg. 2015;2(3):147-157. Published 2015 May 12. doi:10.1002/ams2.104

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