The transition from hyperthyroidism to thyroid storm is typically triggered by a non-thyroidal insult including, but not limited to fever, sepsis, dehydration, myocardial infarction, and psychiatric diseases.[vague][9][8] Individuals are at higher risk of thyroid storm if their hyperthyroidism is incompletely treated or if their anti-thyroid drugs are discontinued. Many of these individuals have underlying primary causes of hyperthyroidism (Graves disease, toxic multi-nodular goiter, solitary toxic adenoma). However, thyroid storm can occur in individuals with unrecognized thyrotoxicosis experiencing non-thyroid surgery, labor, infection, or exposure to certain medications and radiocontrast dyes.
The diagnosis of thyroid storm is based on the presence of symptoms consistent with severe hyperthyroidism, as outlined in the Signs and symptoms section above.[6] Multiple approaches have been proposed to calculate the probability of thyroid storm based on clinical criteria, however, none have been universally adopted by clinicians. For instance, Burch and Wartofsky published the Burch-Wartofsky point scale (BWPS) in 1993, assigning a numerical value based on the presence of specific signs and symptoms organized within the following categories: temperature, cardiovascular dysfunction (including heart rate and presence of atrial fibrillation or congestive heart failure), central nervous system (CNS) dysfunction, gastrointestinal or liver dysfunction and presence of a precipitating event.[6][10] A Burch-Wartofsky score below 25 is not suggestive of thyroid storm whereas 25 to 45 suggests impending thyroid storm and greater than 45 suggests current thyroid storm.[11] Alternatively, the Japanese Thyroid Association (JTA) criteria, derived from a large cohort of patients with thyroid storm in Japan and published in 2012, provide a qualitative method to determine the probability of thyroid storm. The JTA criteria separate the diagnosis of thyroid storm into definite versus suspected based on the specific combination of signs and symptoms a patient exhibits and require elevated free triiodothyronine (T3) or free thyroxine (T4) for definite thyroid storm.[12]
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  headingBody  99.0 to 99.9 5 90 to109 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[edit] => As with hyperthyroidism, TSH is suppressed. Both free and serum (or total) T3 and T4 are elevated.[4] 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.[6][10] Moreover, serum T3 may be normal in critically ill patients due to decreased conversion of T4 to T3.[6] Other potential abnormalities include the following:[6][10]
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
Thyroid storm is characterized by an acute onset of symptoms of hyperthyroidism (fast heart rate, restlessness, agitation) accompanied by other features such as fever (temperatures often above 40 °C/104 °F), mental status changes, diarrhea, and vomiting.[4]
Individuals can exhibit varying signs of organ dysfunction. Patients may experience liver dysfunction, and yellow discoloration of the skin is considered a poor prognostic sign. Heart (cardiac) symptoms include abnormal heart rhythms, decreased blood flow to the heart and heart attacks, and congestive heart failure, which may lead to cardiovascular collapse. Mortality can be as high as 20-30%.[5]
In some situations, individuals may not experience the classic signs of restlessness and agitation, but instead present with apathetic signs of weakness and confusion.[4]