Thyroid storm refers to the life threatening acute presentation of thyroid hormone excess of any cause, typified by pyrexia, tachycardia, neurological disturbance, gastrointestinal upset and heart failure.
Thyroid storm can only be diagnosed in the presence of grossly abnormal thyroid function: undetectable TSH with free thyroxine over 45miu/L.
Pyrexia over 38C, tachycardia >110beats per minute, atrial fibrillation, cardiac failure, agitation or other CNS effects, dehydration and jaundice are the cardinal features of thyroid storm. If none of these are present, the patient does not have thyroid storm and should be assessed and treated for thyrotoxicosis.
Recent criteria developed by the Japanese thyroid association suggest that in the presence of severe biochemical thyrotoxicosis and CNS effects, anyone of fever (38°C or higher), tachycardia (130 beats/min or faster), congestive heart failure or gastrointestinal and hepatic manifestations confirms the diagnosis of thyroid storm.
In the presence of severe biochemical thyrotoxicosis but the absence of CNS effects, any three of those signs suggests thyroid storm.
If some of these features are present but the diagnosis is not absolutely clear, use the Burch and Wartofsky scoring system. Scores above 45 confirm the presence of thyroid storm.
Diagnostic parameters for thyroid storm
Thermoregulatory dysfunction: temperature °C
≥ 40.0 30
Central nervous system effects
Mild agitation 10
Moderate: delirium/extreme lethargy 20
Severe e.g. seizures/coma 30
Moderate: diarrhoea/nausea/abdominal pain 10
Severe (unexplained jaundice) 20
>/= 140 25
Congestive heart failure
Mild (pedal edema) 5
Moderate (bibasal crackles on examination) 10
Severe - clinical pulmonary oedema 15
Atrial fibrillation absent 0
Atrial fibrillation present 10
Precipitating event identified
Precipitating event absent 0
Precipitating event present 10
Hyperpyrexic patients will require cooling.
Intravenous access must be secured to give fluid resuscitation, and consider gaining central access.
Ensure that a full septic screen has been performed: blood and urine cultures, chest radiograph, and treat any possible infective triggers with broad spectrum antibiotics.
Seek any other potential triggers to thyroid storm e.g. myocardial infarction.
Some patients may require emergency sedation, in which case chlorpromazine 50-100mg im is appropriate.
Monitor blood glucose 4-hourly and correct hypoglycaemia.
Propranolol 80mg tds po/propranolol 2mg iv to control tachycardia and improve heart failure.
Propylthiouracil (PTU) 200mg orally, via a nasogastric tube or rectally every 6-8 hours.
This will stop the release of preformed thyroid hormone as well as the production and inter-conversion of thyroid hormones.
Carbimazole 60-80mg daily can be used in addition to PTU.
High dose steroids should be given to block interconversion of thyroxine to liothyronine and are particularly effective in Graves' disease.
An immediate dose of IV Hydrocortisone 200mg should be followed by prednisolone 20mg orally 8-hourly.
Sixty minutes after the first dose of PTU has been given to block iodination, give Lugol’s iodine 5 drops qds po in milk or orange juice.
This can also be used to block the enteric recirculation of thyroid hormones.
Lithium is an effective anti thyroid agent and can be used in addition to conventional anti-thyroid drugs, or as an alternative if these drugs cannot be used e.g. in a patient who has developed agranulocytosis on anti-thyroid drugs.