Hyperthyroidism (Grave’s disease)

Hyperthyroidism is the second most common endocrine disorder and Grave’s disease is the most common type. It results from an excessive output of thyroid hormones due to abnormal stimulation of the thyroid gland  by circulating immunoglobulins. Long-acting thyroid stimulator (LATS) is found significant in concentrations in the serum of many of these patients. The disorder affects women eight times more frequently than men and peaks between the second and fourth decades of life. It may appear after an emotional shock, stress, or infection, but the exact significance of these relationships is not understood. Other common causes include thyroiditis and excessive ingestion of thyroid hormone (eg. from treatment of hypothyroidism)

CLINICAL MANIFESTATIONS

Hyperthyroidism presents a characteristic  group of signs and symptoms (thyrotoxicosis).

  • Nervousness (emotionally hyperexcitable), irritability, apprehensiveness; inability to sit quietly; palpitations, rapid  pulse on rest and exertion.
  • Poor tolerance of heat; excessive perspiration; skin that is flushed and likely to be warm, soft and moist
  • Dry skin and diffuse pruritus in the elderly
  • Fine tremor of the hands
  • Exophthalmos (bulging eyes) in some patients
  • Increased appetite and dietary intake, progressive loss of weight, abnormal muscle fatigability, weakness, amenorrhea, and changes in bowel function (constipation or diarrhea)
  • Pulse ranges between 90 and 160 beats/min with sinus tachycardia or dysrhythmias; systolic (but not diastolic) blood pressure elevation (increased pulse pressure).
  • Atrial fibrillation; cardiac decompensation in the form of congestive heart failure, especially in the elderly
  • Osteoporosis and fracture
  •  May include remissions and exacerbations, terminating with spontaneous recovery in a few months or years
  • May progress relentlessly; causing emaciation, intense nervousness, delirium, disorientation, and eventually myocardial hypertrophy and heart failure.

ASSESSMENT AND DIAGNOSTIC FINDINGS

  • Thyroid glands is enlarged; it is soft and may pulsate; a thrill may be felt and a bruit heard over thyroid arteries
  • Laboratory tests show a decrease in serum TSH, an increase in serum thyroxine (T4) level and an increase in 123I or 125I uptake in excess of 50%.

Gerontologic Considerations

Elderly patients commonly presents with vague and nonspecific signs and symptoms. The major symptoms in the elderly patient may be depression and apathy, accompanied by significant weight loss and constipation in some. The patient may report cardiovascular symptoms and difficulty climbing stairs  or rising from a chair because of muscle weakness; congestive failure may be noted. Elderly patients may experience a single manifestation, such as atrial fibrillation, anorexia, or weight loss.  These general symptoms may mask underlying thyroid disease. Spontaneous remission of hyperthyroidism is rare in the elderly. Measurement of thyroid-stimulating hormone (TSH) uptake is indicated in elderly patients with unexplained physical or mental deterioration . Use of 123I or 131I is generally recommended for treatment of thyrotoxicosis rather than surgery unless an enlarged thyroid gland is pressing on the airway. Thyrotoxicosis must be controlled by antithyroid drugs before 131I is used because radiation may precipitate thyroid storm, which has a high mortality rate in the elderly.  Beta-blockers may be indicated. Use these agents with extreme caution ans monitor closely for granulocytopenia. Modify dosages of other medications because of the altered rate of metabolism in hyperthyroidism.

MEDICAL MANAGEMENT

Treatment is directed toward reducing thyroid hyperactivity for symptomatic relief and removing the cause of complications. These forms of treatment are available:

  • Irradiation involving the administration of 131I or 123I for destructive effects on the thyroid gland.
  • Pharmacotherapy with antithyroid medications.
  • Surgery with the removal of the most of the thyroid gland.

Radioactive Iodine (131 I)

  • 131 I is given to destroy the overactive thyroid cells (most common in the elderly).
  • 131 I is contraindicated in pregnancy and nursing mothers because radioiodine crosses the placenta and is secreted in breast milk.

Pharmacotherapy

  • The objective of pharmacotherapy is to inhibit hormone synthesis or release and reduce the amount of thyroid tissue.
  • The most commonly used medicatioins are propylthiouracil (Propacil, PTU) and methimazole (Tapazole) until patient is euthyroid.
  • Maintenance dose is established, followed by gradual withdrawal of the medication over the next several months.
  • Antithyroid drugs are contraindicated in late pregnancy because of the risk for goiter and cretinism in the fetus.
  • Thyroid hormone may be administered to put the thyroid to rest.

Adjunctive Therapy

  • Potassium iodide, Lugol’s solution, and saturated solution of potassium iodide (SSKI) may be added.
  • Beta-adrenergic agents may be used to control the sympathetic nervous system effects that occur in hyperthyroidism; for example; propanolol is used for nervousness, tachycardia, tremor, anxiety, and heat intolerance.

Surgical Intervention

  • Surgical intervention (reserved for special circumstances)removes about five sixths of the thyroid tissue.
  • Before surgery, the patient is given propylthiouracil until signs of hyperthyroidism have disappeared.
  • Iodine is prescribed to reduce the thyroid size and vascularity and blood loss. Patient is monitored carefully for evidence of iodine toxicity (swelling buccal mucosa, excessive salivation, skin eruptions).
  • Risk for relapse and complications necessitates long-term follow-up of patient undergoing treatment of hyperthyroidism.
  • Surgery to treat hyperthyroidism is performed after thyroid function has returned to normal (4 to 6 weeks).

 

Reference:

Handbook for Brunner & Suddarth’s Textbook of Medical-Surgical Nursing 11th edition by Joyce Young Johnson

Lippincott Williams and Wilkins pp.461-464

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