eMedicine Specialties > Pediatrics: General Medicine > Endocrinology

Thyroid Storm

Author: Madhusmita Misra, MD, Assistant in Pediatrics, Mass General Hospital for Children, Harvard Medical School; Assistant Professor of Pediatrics, Fellowship Program Director, Department of Pediatric Endocrinology, Massachusetts General Hospital
Coauthor(s): Abhay Singhal, MD, Assistant Professor of Clinical Pediatrics, Department of Pediatrics, Division of Neonatology, Indiana University School of Medicine; Deborah E Campbell, MD, Professor of Clinical Pediatrics, Albert Einstein College of Medicine; Director, Department of Pediatrics, Division of Neonatology, Weiler Hospital Division of Montefiore Medical Center
Contributor Information and Disclosures

Updated: Jun 4, 2009

Introduction

Background

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.

Pathophysiology

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.

Clinical

History

Patients may have a known history of thyrotoxicosis. In the absence of previously diagnosed thyrotoxicosis, the history may include symptoms such as irritability, agitation, emotional lability, a voracious appetite with poor weight gain, excessive sweating and heat intolerance, and poor school performance caused by decreased attention span. Burch and Wartofsky have published precise criteria and a scoring system for the diagnosis of thyroid storm based on clinical features.²

• General symptoms
  • Fever
  • Profuse sweating
  • Poor feeding and weight loss
  • Respiratory distress
  • Fatigue (more common in older adolescents)
• GI symptoms
  • Nausea and vomiting
  • Diarrhea
  • Abdominal pain
  • Jaundice³
• Neurologic symptoms
  • Anxiety (more common in older adolescents)
  • Altered behavior
  • Seizures, coma

Physical

• Fever
  • Temperature consistently exceeds 38.5°C.
  • Patients may progress to hyperpyrexia.
  • Temperature frequently exceeds 41°C.
• Excessive sweating
• Cardiovascular signs
  • Hypertension with wide pulse pressure
  • Hypotension in later stages with shock
  • Tachycardia disproportionate to fever
  • Signs of high-output heart failure
  • Cardiac arrhythmia (Supraventricular arrhythmias are more common, [eg, atrial flutter and fibrillation], but ventricular tachycardia may also occur.)
• Neurologic signs
  • Agitation and confusion
  • Hyperreflexia and transient pyramidal signs
  • Tremors, seizures
  • Coma
• Signs of thyrotoxicosis
  • Orbital signs
  • Goiter

Causes

• Thyroid storm is precipitated by the following factors in individuals with thyrotoxicosis:
  • Sepsis
  • Surgery
  • Anesthesia induction⁴
  • Radioactive iodine (RAI) therapy⁵
  • Drugs (anticholinergic and adrenergic drugs such as pseudoephedrine; salicylates; nonsteroidal anti-inflammatory drugs [NSAIDs]; chemotherapy⁶ )
  • Excessive thyroid hormone 9TH) ingestion
  • Withdrawal of or noncompliance with antithyroid medications
  • Diabetic ketoacidosis
  • Direct trauma to the thyroid gland
  • Vigorous palpation of an enlarged thyroid
  • Toxemia of pregnancy and labor in older adolescents; molar pregnancy
• Thyroid storm can occur in children with thyrotoxicosis due to any cause but is most commonly associated with Graves disease. Other reported causes of thyrotoxicosis associated with thyroid storm include the following:
  • Transplacental passage of maternal thyroid-stimulating immunoglobulins in neonates
  • McCune-Albright syndrome with autonomous thyroid function⁷
  • Hyperfunctioning thyroid nodule
  • Hyperfunctioning multinodular goiter
  • Thyroid-stimulating hormone (TSH)–secreting tumor
• Graves disease may also occur in children with Down syndrome or Turner syndrome and in association with other autoimmune conditions, including the following:
  • Juvenile rheumatoid arthritis
  • Addison disease
  • Type I diabetes
  • Myasthenia gravis
  • Chronic lymphocytic (Hashimoto) thyroiditis
  • Systemic lupus erythematosus
  • Chronic active hepatitis
  • Nephrotic syndrome
• Although the exact pathogenesis of thyroid storm is not fully understood, the following theories have been proposed:
  • Patients with thyroid storm reportedly have relatively higher levels of free THs than patients with uncomplicated thyrotoxicosis, although total TH levels may not be increased.
  • Adrenergic receptor activation is another hypothesis. Sympathetic nerves innervate the thyroid gland, and catecholamines stimulate TH synthesis. In turn, increased THs increase the density of beta-adrenergic receptors, thereby enhancing the effect of catecholamines. The dramatic response of thyroid storm to beta-blockers and the precipitation of thyroid storm after accidental ingestion of adrenergic drugs such as pseudoephedrine support this theory. This theory also explains normal or low plasma levels and urinary excretion rates of catecholamines. However, it does not explain why beta-blockers fail to decrease TH levels in thyrotoxicosis.
  • Another theory suggests a rapid rise of hormone levels as the pathogenic source. A drop in binding protein levels, which may occur postoperatively, might cause a sudden rise in free hormone levels. In addition, hormone levels may rise rapidly when the gland is manipulated during surgery, during vigorous palpation during examination, or from damaged follicles following RAI therapy.
  • Other proposed theories include alterations in tissue tolerance to THs, the presence of a unique catecholaminelike substance in thyrotoxicosis, and a direct sympathomimetic effect of TH as a result of its structural similarity to catecholamines.

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