Hyperthyroidism

(Graves’ Disease, Thyrotoxicosis, Toxic Diffuse Goiter, Toxic Nodular Goiter, Plummer’s Disease, Basedow’s Disease)

– A syndrome initiated by excessive production of thyroid hormones that results in multiple-system abnormalities ranging from mild to severe.

Causes and Incidence

The cause of hyperthyroidism is unclear, but it is thought to be autoimmune in origin with a genetic component. The most common type of hyperthyroidism is Graves’ disease, which occurs about eight times more often in women than men and is seen in about 2% of the female population in the United States.

Disease Process

Thyroid hormones are generally stimulatory, and excess production of these hormones produces a state of hypermetabolism in which the functions of various organ and tissue systems are increased. This is manifested by increased activity of the neuromuscular and sympathetic nervous systems. Compensatory mechanisms are called into play, and cardiac output, peripheral blood flow, body temperature, and respiratory rate increase. Other effects include increased cellular use of glucose and hyperinsulinemia, decreased supply of fats and carbohydrates, increased vitamin metabolism, increased bone mobilization and hypercalcemia, and increased secretion of adrenocorticotropic hormone and melanocyte-stimulating hormone. The organ systems eventually have trouble coping with the increased demand, and failure can result.

Symptoms

The most common signs are goiter; warm, moist skin; erythema; sweating; tremor; weakness; restlessness; insomnia; emotional lability; increased food intake; lid lag; lid retraction; proptosis; tearing; and a startled look.

Potential Complications

Cardiac insufficiency, generalized muscle wasting, corneal ulcers, decreased libido, osteoporosis, myasthenia gravis, and impaired fertility are among the complications. The elderly are the most likely to exhibit these complications. Thyroid storm is a severe, dramatic form of hyperthyroidism with an abrupt onset and rapid progression. It is a life-threatening emergency requiring immediate treatment to prevent shock, coma, cardiovascular collapse, and death.

Diagnostic Tests

Diagnosis depends on the clinical history and examination coupled with a serum triiodothyronine and thyroxine assay and thyroid hormone binding ratio. All of the laboratory test results are elevated in hyperthyroidism.

Treatments

Surgery
Thyroidectomy in individuals who cannot receive radioactive iodine, have large goiters, or have toxic adenoma.

Drugs
Radioactive iodine to destroy thyroid tissue (treatment of choice); thiamides to inhibit hormone synthesis; beta-adrenergic blockers to diminish clinical manifestations; iodines to reduce the size of the thyroid before surgery; corticosteroids for palliation in Graves’ disease.

General
Monitoring for signs of hypothyroidism; planned rest and exercise cycles; long-term follow-up; counseling for lability; instruction about medications.