Definition: Thyroid storm, is a life-threatening medical emergency in which excessive concentrations of thyroid hormone produce organ dysfunction. It is an uncommon manifestation of hyperthyroidism.
Precipitating factors:
- Severe infection.
- Diabetic ketoacidosis.
- Direct trauma or surgical manipulation of the thyroid gland.
- Iodine, either from excessive ingestion, intravenous administration, or radiotherapy.
- Discontinuation of antithyroid medications.
- Of interest, salicylates have been implicated in triggering thyroid storm by increasing the concentration of circulating free thyroid hormones to critical levels.
Clinical manifestation & Diagnosis
The diagnosis of thyroid storm relies heavily on clinical suspicion.
- Thermoregulatory dysfunction---- (high fever, warm moist skin, diaphoresis)
- Neurologic manifestations---- (mental status changes, seizure, coma, psychosis, hyperreflexia, lid lag)
- Cardiovascular dysregulation---- (atrial fibrillation, tachycardia, hypertension, congestive heart failure)
- Respiratory distress---- (dyspnea, tachypnea)
- Gastrointestinal dysfunction---- (diarrhea, abdominal pain, nausea, vomiting)
Confirmed by means of thyroid function tests (TFT). However, treatment should not be delayed for verification by laboratory tests.
N.B.- Because of increased conversion of T4 to T3, the elevation of T3 is typically more dramatic. For this reason it is essential to measure both T3 and free T4 levels
There are no differences in the results of TFT in patients with thyroid storm when compared with patients who have symptomatic hyperthyroidism, and levels of thyroid hormone cannot predict which patients will undergo decompensation from thyrotoxicosis to thyroid storm.
Other laboratory abnormalities are:
- Hypercalcemia from osteoclast-mediated bone resorption.
- Elevated alkaline phosphatase caused by activated bone remodeling.
- Hyperglycemia secondary to enhanced glycogenolysis and increased circulation of catecholamines.
- Adrenal insufficiency, especially among patients with Graves disease, is common and should be evaluated prior to the initiation of treatment.
Treatment of Thyroid storm
The treatment of thyroid storm involves 3 critical fundamentals.
- First, supportive care should be provided to minimize the secondary effects of organ failure.This should include respiratory and hemodynamic support and treatment of hyperthermia.
- Second, identification and treatment of the precipitating event.
- Third, and most critical, the release and effects of circulating thyroid hormone must be blocked.
Medications:
- Propylthiouracil (PTU) blocks peripheral conversion of T4 to T3 and can be given as a 600- to 1000-mg loading dose, followed by 1200 mg/day divided into doses given every 4 to 6 hours.
- Beta-blockers; typically propranolol administered intravenously initially in 1-mg increments every 10 to 15 minutes until symptoms are controlled (tachycardia and hypertension)
- Hydrocortisone 100 mg given intravenously every 8 hours
- Lithium & Iodine act by inhibiting hormone release but should not be given until 1 hour after PTU administration.
- In refractory cases, plasmapheresis, plasma exchange, and peritoneal hemodialysis can be used to remove circulating thyroid hormone.
Prognosis of Thyroid storm
- With appropriate treatment, clinic and biochemical improvement are typically seen within 24 hours. Full recovery usually occurs within a week of therapy.
- If untreated, is associated with 80% to 90% mortality. Even with treatment, mortality from thyroid storm exceeds 20%.
