Thyroid Storm 

Thyroid storm, also referred to as thyrotoxic crisis, is an acute, life-threatening, hypermetabolic state induced by excessive release of thyroid hormones (THs) in individuals with thyrotoxicosis. Thyroid storm may be the initial presentation of thyrotoxicosis in undiagnosed children, particularly in neonates. The clinical presentation includes fever, tachycardia, hypertension, and neurological and GI abnormalities. Hypertension may be followed by congestive heart failure that is associated with hypotension and shock. Because thyroid storm is almost invariably fatal if left untreated, rapid diagnosis and aggressive treatment are critical. Fortunately, this condition is extremely rare in children.

Diagnosis is primarily clinical, and no specific laboratory tests are available. Several factors may precipitate the progression of thyrotoxicosis to thyroid storm. In the past, thyroid storm was commonly observed during thyroid surgery, especially in older children and adults, but improved preoperative management has markedly decreased the incidence of this complication. Today, thyroid storm occurs more commonly as a medical crisis rather than a surgical crisis.

Thyroid storm is a decompensated state of thyroid hormone–induced, severe hypermetabolism involving multiple systems and is the most extreme state of thyrotoxicosis. The clinical picture relates to severely exaggerated effects of THs due to increased release (with or without increased synthesis) or, rarely, increased intake of TH.

Heat intolerance and diaphoresis are common in simple thyrotoxicosis but manifest as hyperpyrexia in thyroid storm. Extremely high metabolism also increases oxygen and energy consumption. Cardiac findings of mild-to-moderate sinus tachycardia in thyrotoxicosis intensify to accelerated tachycardia, hypertension, high-output cardiac failure, and a propensity to develop cardiac arrhythmias. Similarly, irritability and restlessness in thyrotoxicosis progress to severe agitation, delirium, seizures, and coma.^[1] GI manifestations of thyroid storm include diarrhea, vomiting, jaundice, and abdominal pain, in contrast to only mild elevations of transaminases and simple enhancement of intestinal transport in thyrotoxicosis.

Frequency

United States

The true frequency of thyrotoxicosis and thyroid storm in children is unknown. The incidence of thyrotoxicosis increases with age. Thyrotoxicosis may affect as many as 2% of older women. Children constitute less than 5% of all thyrotoxicosis cases. Graves disease is the most common cause of childhood thyrotoxicosis and, in a possibly high estimate, reportedly affects 0.2-0.4% of the pediatric and adolescent population. About 1-2% of neonates born to mothers with Graves disease manifest thyrotoxicosis.

Mortality/Morbidity

Thyroid storm is an acute, life-threatening emergency. The adult mortality rate is extremely high (90%) if early diagnosis is not made and the patient is left untreated. With better control of thyrotoxicosis and early management of thyroid storm, adult mortality rates have declined to less than 20%.

Sex

Thyrotoxicosis is 3-5 times more common in females than in males, especially among pubertal children. Thyroid storm affects a small percentage of patients with thyrotoxicosis. The incidence is presumed to be higher in females; however, no specific data regarding sex-specific incidence are available.

Age

Neonatal thyrotoxicosis occurs in 1-2% of neonates born to mothers with Graves disease. Infants younger than 1 year constitute only 1% of childhood thyrotoxicosis. More than two thirds of all cases of thyrotoxicosis occur in children aged 10-15 years. Overall, thyrotoxicosis occurs most commonly during the third and fourth decades of life. Because childhood thyrotoxicosis is more likely to occur in adolescents, thyroid storm is more common in this age group, although it can occur in patients of all ages.