Thyroid storm
Thyroid storm | |
---|---|
Other names | Thyrotoxic crisis |
infectious disease[1] | |
Prognosis | 8-25% mortality with treatment; 80-100% mortality if untreated |
Thyroid storm is a rare but severe and life-threatening complication of
It is characterized by a
The primary treatment of thyroid storm is with inorganic iodine and antithyroid drugs (
As a life-threatening medical emergency, thyroid storm has a mortality rate of up to 25% despite treatment.[1][7] Without treatment, the condition is typically fatal, with a mortality rate of 80-100%.[8] Historically, the condition was considered untreatable, with hospital mortality rates approaching 100%.[9][10]
Signs and symptoms
Thyroid storm is characterized by an acute onset of symptoms of hyperthyroidism (
Individuals can exhibit varying signs of organ dysfunction. Patients may experience liver dysfunction, and
In some situations, individuals may not experience the classic signs of restlessness and agitation, but instead present with apathetic signs of weakness and confusion.[11]
Causes
The transition from hyperthyroidism to thyroid storm is typically triggered by a non-thyroidal insult including, but not limited to
Severe infection |
Diabetic ketoacidosis |
Hypoglycemia |
Thyroid surgery |
Non-thyroid surgery |
Parturition
|
Struma ovarii |
Molar pregnancy |
Trauma (i.e. hip fracture) |
Burns |
Myocardial infarction |
Pulmonary embolism |
Stroke |
Heart failure |
Radioactive iodine treatment |
Medication side effect (anesthetics, salicylate, pseudoephedrine, amiodarone) |
Exposure to iodinated contrast |
Withdrawal of antithyroid treatment |
Emotional stress |
Intense exercise |
Pathophysiology
The precise mechanism for the development of thyroid storm is poorly understood. In the human body,
Increases in free thyroid hormone
Individuals with thyroid storm tend to have increased levels of free thyroid hormone, although total thyroid hormone levels may not be much higher than in uncomplicated hyperthyroidism.[15] The rise in the availability of free thyroid hormone can be the result of manipulating the thyroid gland. In an individual receiving radioactive iodine therapy, free thyroid hormone levels can acutely increase due to the release of hormone from ablated thyroid tissue.[citation needed]
Decrease in thyroid hormone binding protein
A decrease in thyroid hormone binding protein under the effects of stressors or medications may also cause a rise in free thyroid hormone.[5]
Increased sensitivity to thyroid hormone
Along with increases in thyroid hormone availability, it is suggested that thyroid storm is characterized by the body's heightened sensitivity to thyroid hormone, which may be related to sympathetic activation.[15]
Sympathetic activation
Thyroid storm as allostatic failure
According to newer theories, thyroid storm results from
Usually, in
These newer theories imply that thyroid storm results from an interaction of thyrotoxicosis with the specific response of the organism to an oversupply of thyroid hormones.[13]
Diagnosis
The diagnosis of thyroid storm is based on the presence of signs and symptoms consistent with severe
Temperature | Score | Heart Rate | Score | Symptoms of Heart Failure | Score | Presence of Atrial Fibrillation | Score | Symptoms of CNS Dysfunction | Score | Gastrointestinal or Liver Dysfunction | Score | Presence of Precipitating Event | Score |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
99.0 to 99.9 | 5 | 90 to 109 | 5 | None | 0 | Absent | 0 | None | 0 | None | 0 | None | 0 |
100.0 to 100.9 | 10 | 110 to 119 | 10 | Mild (i.e. pedal edema) | 5 | Present | 10 | Mild (e.g. showing signs of agitation) | 10 | Moderate (e.g. diarrhea, nausea, vomiting or abdominal pain) | 10 | Present | 10 |
101.0 to 101.9 | 15 | 120 to 129 | 15 | Moderate (i.e. bibasilar rales) | 10 | Moderate (e.g. delirium, psychosis, lethargy) | 20 | Severe (i.e. unexplained jaundice) | 20 | ||||
102.0 to 102.9 | 20 | 130 to 139 | 20 | Severe (i.e. pulmonary edema) | 15 | Severe (e.g. seizure or coma) | 30 | ||||||
103 to 103.9 | 25 | Greater than or equal to 140 | 25 | ||||||||||
Greater than or equal to 104 | 30 |
Laboratory findings
As with hyperthyroidism, TSH is suppressed. Both free and serum (or total) T3 and T4 are elevated.[11] An elevation in thyroid hormone levels is suggestive of thyroid storm when accompanied by signs of severe hyperthyroidism but is not diagnostic as it may also correlate with uncomplicated hyperthyroidism.[15][18] Moreover, serum T3 may be normal in critically ill patients due to decreased conversion of T4 to T3.[15] Other potential abnormalities include the following:[15][18]
- Hyperglycemia likely due to catecholamine-mediated effects on insulin release and metabolism as well as increased glycogenolysis, evolving into hypoglycemia when glycogen stores are depleted
- Elevated aspartate aminotransferase (AST), bilirubin and lactate dehydrogenase(LDH)
- Hypercalcemia and elevated alkaline phosphatase due to increased bone resorption
- Elevated white blood cell count
Management
The main strategies for the management of thyroid storm are reducing production and release of thyroid hormone, reducing the effects of thyroid hormone on tissues, replacing fluid losses, and controlling temperature.
In high fever, temperature control is achieved with fever reducers such as paracetamol/acetaminophen and external cooling measures (cool blankets, ice packs). Dehydration, which occurs due to fluid loss from sweating, diarrhea, and vomiting, is treated with frequent fluid replacement.[21] In severe cases, mechanical ventilation may be necessary. Any suspected underlying cause is also addressed.[4]
Iodine
Guidelines recommend the administration of inorganic iodide (
Antithyroid medications
Antithyroid drugs (
Colestyramine
Colestyramine is an oral bile acid sequestrant used to reduce levels of circulating thyroid hormone in thyrotoxic patients by interfering with the enterohepatic circulation and thyroid hormone recycling. Cholestyramine use is usually reserved for patients who are intolerant of the other antithyroid medications.[25]
Beta blockers
The administration of
Propranolol at high doses is a common first-line treatment, as it reduces peripheral conversion of T4 to T3, which is the more active form of thyroid hormone.[26][21] Non-selective beta blockers have been suggested to be beneficial due to their inhibitory effects on peripheral deiodinases. Some recent research suggests them to be associated with increased mortality.[27] Therefore, cardioselective beta blockers may be favourable.[14]
Corticosteroids
High levels of thyroid hormone result in a hypermetabolic state, which can result in increased breakdown of cortisol, a hormone produced by the adrenal gland. This results in a state of relative adrenal insufficiency, in which the amount of cortisol is not sufficient.[27] Guidelines recommend that corticosteroids (hydrocortisone and dexamethasone are preferred over prednisolone or methylprednisolone) be administered to all patients with thyroid storm. However, doses should be altered for each individual patient to ensure that the relative adrenal insufficiency is adequately treated while minimizing the risk of side effects.[27]
Plasmapheresis
Plasmapheresis removes cytokines, antibodies, and thyroid hormones from the plasma.[28] It is usually reserved for severe refractory cases of thyroid storm as a bridge to surgery.[29]
Supportive care
Patients with thyroid storm are usually hospitalized and managed in the intensive care unit. Supportive measures include treatment of precipitating factors (e.g. infection), intravenous fluids, and cooling blankets and ice packs for persistent fever. Extracorporeal membrane oxygenation (ECMO) can been used as a bridging measure for refractory cardiorespiratory failure induced by thyroid storm.[30]
See also
References
- ^ PMID 28846289. Retrieved 2023-05-28.
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- ^ "Thyroid Storm Clinical Presentation: History, Physical Examination, Complications".
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- ^ "Gathering Storm: Treating the Once Fatal Thyroid Storm". Endocrine News. 2014-08-01. Retrieved 2023-05-28.
- ^ Misra M (2023-02-02). "Thyroid Storm: Practice Essentials, Pathophysiology, Etiology". Medscape Reference. Retrieved 2023-05-28.
- ^ a b c d Gardner DG (2017). "Endocrine Emergencies". In Gardner DG, Shoback D (eds.). Greenspan's Basic and Clinical Endocrinology (10 ed.). New York: McGraw-Hill.
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