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Hyperthyroidism, Thyroid Storm, and Graves Disease

  • Author: Erik D Schraga, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
Updated: May 30, 2014


Hyperthyroidism, thyroid storm, and Graves disease are conditions of excess thyroid hormone. The elevated level of thyroid hormones can result in clinical manifestations ranging from mild to severely toxic with resultant morbidity and mortality for affected patients.


Hyperthyroidism presents as a constellation of symptoms due to elevated levels of circulating thyroid hormones. Because of the many actions of thyroid hormone on various organ systems in the body, the spectrum of clinical signs produced by the condition is broad. The presenting symptoms can be subtle and nonspecific, making hyperthyroidism difficult to diagnose in its early stages without the aid of laboratory data.

The term hyperthyroidism refers to inappropriately elevated thyroid function. Though often used interchangeably, the term thyrotoxicosis, which is an excessive amount of circulating thyroid hormone, is not synonymous with hyperthyroidism. Increased levels of hormone can occur despite otherwise normal thyroid function, such as in instances of inappropriate exogenous thyroid hormone or excessive release of stored hormone from an inflamed thyroid gland.

Graves disease

Graves disease (diffuse toxic goiter), the most common form of overt hyperthyroidism, is an autoimmune condition in which autoantibodies are directed against the thyroid-stimulating hormone (TSH) receptor. As a result, the thyroid gland is inappropriately stimulated with ensuing gland enlargement and increase of thyroid hormone production. Risk factors for Graves disease include family history of hyperthyroidism or various other autoimmune disorders, high iodine intake, stress, use of sex steroids, and smoking. The disease is classically characterized by the triad of goiter, exophthalmos, and pretibial myxedema.

Thyroid storm

Thyroid storm is a rare and potentially fatal complication of hyperthyroidism. It typically occurs in patients with untreated or partially treated thyrotoxicosis who experience a precipitating event such as surgery, infection, or trauma. Thyroid storm must be recognized and treated on clinical grounds alone, as laboratory confirmation often cannot be obtained in a timely manner. Patients typically appear markedly hypermetabolic with high fevers, tachycardia, nausea and vomiting, tremulousness, agitation, and psychosis. Late in the progression of disease, patients may become stuporous or comatose with hypotension.

For more information, see Medscape's Thyroid Disease Resource Center.



In healthy patients, the hypothalamus produces thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary gland to secrete thyroid-stimulating hormone (TSH); this in turn triggers the thyroid gland to synthesize thyroid hormone.

Thyroid hormone concentration is regulated by negative feedback by circulating free hormone primarily on the anterior pituitary gland and to a lesser extent on the hypothalamus. The secretion of TRH is also partially regulated by higher cortical centers.

The thyroid gland produces the prohormone thyroxine (T4), which is deiodinated primarily by the liver and kidneys to its active form, triiodothyronine (T3). The thyroid gland also produces a small amount of T3 directly. T4 and T3 exist in 2 forms: a free, unbound portion that is biologically active and a portion that is protein bound to thyroid-binding globulin (TBG). Despite consisting of less than 0.5% of total circulating hormone, free or unbound T4 and T3 levels best correlate with the patient's clinical status.




United States

The overall incidence of hyperthyroidism is estimated between 0.05% and 1.3%, with the majority consisting of subclinical disease. A population-based study in the United Kingdom and Ireland found an incidence of 0.9 cases per 100,000 children younger than 15 years, showing that the disease incidence increases with age.[1] The prevalence of hyperthyroidism is approximately 5-10 times less than hypothyroidism.

Thyroid storm is a rare disorder. Approximately 1-2% of patients with hyperthyroidism progress to thyroid storm.


See the list below:

  • Thyroid storm, if unrecognized and untreated, is often fatal.
  • Adult mortality rate from thyroid storm is approximately 10-20%, but it has been reported to be as high as 75% in hospitalized populations. Underlying precipitating illness may contribute to high mortality.


See the list below:

  • White and Hispanic populations in the United States have a slightly higher prevalence of hyperthyroidism in comparison with black populations.


See the list below:

  • A slight predominance of hyperthyroidism exists among females.


See the list below:

  • Thyroid storm may occur at any age but is most common in those in their third through sixth decades of life.
  • Graves disease predominantly affects those aged 20-40 years.
  • The prevalence of toxic multinodular goiter increases with age and becomes the primary cause of hyperthyroidism in elderly persons.
Contributor Information and Disclosures

Erik D Schraga, MD Staff Physician, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Howard A Bessen, MD Professor of Medicine, Department of Emergency Medicine, University of California, Los Angeles, David Geffen School of Medicine; Program Director, Harbor-UCLA Medical Center

Howard A Bessen, MD is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Chief Editor

Romesh Khardori, MD, PhD, FACP Professor of Endocrinology, Director of Training Program, Division of Endocrinology, Diabetes and Metabolism, Strelitz Diabetes and Endocrine Disorders Institute, Department of Internal Medicine, Eastern Virginia Medical School

Romesh Khardori, MD, PhD, FACP is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Physicians, American Diabetes Association, Endocrine Society

Disclosure: Nothing to disclose.

Additional Contributors

Robin R Hemphill, MD, MPH Associate Professor, Director, Quality and Safety, Department of Emergency Medicine, Emory University School of Medicine

Robin R Hemphill, MD, MPH is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

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