Thyroid Gland

Thyroid Gland

• Located in the anterior part of the neck

• Controls the rate of body metabolism and growth and produces Thyroxine (T4), Triiodothyronine (T3), and Thyrocalcitonin

Diagnostics

Radioactive Iodine Uptake

• This thyroid function test measures the absorption of an iodine isotope to determine how the thyroid gland is functioning.

• A small dose of radioactive iodine is given by mouth or intravenously; the amount of radioactivity is measured in 2 to 4 hours and again at 24 hours.

• Normal values are 3% to 10% at 2 to 4 hours, and 5% to 30% in 24 hours

Diagnostics

Thyroid Stimulating Hormone

• Blood test is used to differentiate the diagnosis of primary hypothyroidism.

• Normal value is 2–10 mcU/L (2–10 mU/L).

• Elevated values indicate primary hypothyroidism.

• Decreased values indicate hyperthyroidism or secondary hypothyroidism

Diagnostics

Thyroid Scan

• A thyroid scan is performed to identify nodules or growths in the thyroid gland.

• A radioisotope of iodine or technetium is administered before scanning the thyroid gland.

• Reassure the client that the level of radioactive medication is not dangerous to self or others.

• Determine whether the client has received radiographic contrast agents within the past 3 months, because these may invalidate the scan.

• Check with the health care provider (HCP) regarding discontinuing medications containing iodine for 14 days before the test and the need to discontinue thyroid medication before the test.

• Instruct the client to maintain NPO (nothing by mouth) status after midnight on the day before the test; if iodine is used, the client will fast for an additional 45 minutes after ingestion of the oral isotope and the scan will be performed in 24 hours.

• If technetium is used, it is administered by the intravenous (IV) route 30 minutes before the scan.

• The test is contraindicated in pregnancy

Diagnostics

Needle Aspiration of Thyroid Tissue

• Aspiration of thyroid tissue is done for cytological examination.

• No client preparation is necessary; NPO status may or may not be prescribed.

• Light pressure is applied to the aspiration site after the procedure.

Hypothyroidism

• A state resulting from hyposecretion of thyroid hormones and characterized by a decreased rate of body metabolism

• The T4 is low and the TSH is elevated.

• In primary hypothyroidism, the source of dysfunction is the thyroid gland and the thyroid cannot produce the necessary amount of hormones.

• In secondary hypothyroidism, the thyroid is not being stimulated by the pituitary to produce hormones.

Assessment of Hypothyroidism

• Lethargy and fatigue

• Weakness, muscle aches, paresthesia

• Intolerance to cold

• Weight gain

• Dry skin and hair and loss of body hair

• Bradycardia

• Constipation

• Generalized puffiness and edema around the eyes and face (myxedema)

• Forgetfulness and loss of memory

• Menstrual disturbances

• Goiter may or may not be present

• Cardiac enlargement, tendency to develop heart failure

Management of Hypothyroidism

• Monitor vital signs, including heart rate and rhythm

• Administer thyroid replacement; levothyroxine sodium is most commonly prescribed.

• Instruct the client about thyroid replacement therapy and about the clinical manifestations of both hypothyroidism and hyperthyroidism related to under replacement or overreplacement of the hormone.

• Instruct the client in a low-calorie, low cholesterol, low–saturated fat diet; discuss a daily exercise program such as walking.

• Assess the client for constipation; provide roughage and fluids to prevent constipation.

• Provide a warm environment for the client

• Avoid sedatives and opioid analgesics because of increased sensitivity to these medications; may precipitate myxedema coma.

• Monitor for overdose of thyroid medications, characterized by tachycardia, chest pain, restlessness, nervousness, and insomnia.

• Instruct the client to report episodes of chest pain or other signs of overdose immediately

Myxedema Coma

• This rare but serious disorder results from persistently low thyroid production.

• Coma can be precipitated by acute illness, rapid withdrawal of thyroid medication, anesthesia and surgery, hypothermia, or the use of sedatives and opioid analgesics

Assessment of Myxedema Coma

• Hypotension

• Bradycardia

•  Hypothermia

• Hyponatremia

• Hypoglycemia

• Generalized edema

• Respiratory failure

• Coma

Management of Myxedema Coma

• Maintain a patent airway.

• Institute aspiration precautions.

• Administer IV fluids (Normal or hypertonic saline) as prescribed.

• Administer levothyroxine sodium intravenously as prescribed.

• Administer glucose intravenously as prescribed.

• Administer corticosteroids as prescribed.

• Assess the client’s temperature hourly.

• Monitor blood pressure frequently.

• Keep the client warm.

• Monitor for changes in mental status.

• Monitor electrolyte and glucose levels

Hyperthyroidism

• Hyperthyroid state resulting from hypersecretion of thyroid hormones (T3 and T4)

• Characterized by an increased rate of body metabolism

• A common cause is Graves’ disease, also known as toxic diffuse goiter.

• Clinical manifestations are referred to as thyrotoxicosis.

• The T3 and T4 are usually elevated and the TSH level is low

Assessment of Hyperthyroidism

• Personality changes such as irritability, agitation, and mood swings

• Nervousness and fine tremors of the hands

• Heat intolerance

• Weight loss

• Smooth, soft skin and hair

• Palpitations, cardiac dysrhythmias, such as tachycardia or atrial fibrillation

• Diarrhea

• Protruding eyeballs (Exophthalmos) may be present

• Diaphoresis

• Hypertension 

• Enlarged thyroid gland (Goiter)

Interventions of Hyperthyroidism

• Provide adequate rest.

• Administer sedatives as prescribed.

• Provide a cool and quiet environment.

• Obtain weight daily.

• Provide a high-calorie diet.

• Avoid the administration of stimulants.

• Administer antithyroid medications, such as methimazole or propylthiouracil that block thyroid synthesis as prescribed.

• Administer iodine preparations that inhibit the release of thyroid hormone as prescribed.

• Administer propranolol for tachycardia as prescribed

• Prepare the client for radioactive iodine therapy, as prescribed, to destroy thyroid cells.

• Prepare the client for subtotal thyroidectomy if prescribed.

• Elevate the head of the bed of a client experiencing exophthalmos; in addition, instruct on low-salt diet, administer artificial tears, encourage the use of dark glasses, and tape eyelids closed at night if necessary.

• Allow the client to express concerns about body image changes

Thyroid Storm

• This acute and life-threatening condition occurs in a client with uncontrollable hyperthyroidism.

• It can be caused by manipulation of the thyroid gland during surgery and the release of thyroid hormone into the bloodstream; it also can occur from severe infection and stress

• Antithyroid medications, beta blockers, glucocorticoids, and iodides may be administered to the client before thyroid surgery to prevent its occurrence

Assessment of Thyroid Storm

• Elevated temperature (fever)

• Tachycardia

• Systolic hypertension

• Nausea, vomiting, and diarrhea

• Agitation, tremors, anxiety

• Irritability, agitation, restlessness, confusion, and seizures as the condition progresses

• Delirium and coma

Management of Thyroid Storm

• Maintain a patent airway and adequate ventilation.

• Administer antithyroid medications, iodides, propranolol, and glucocorticoids as prescribed.

• Monitor vital signs

•  Monitor continually for cardiac dysrhythmias.

• Administer non salicylate antipyretics as prescribed (salicylates increase free thyroid hormone levels). 

• Use a cooling blanket to decrease temperature as prescribed.

Thyroidectomy

• Removal of the thyroid gland

• Performed when persistent hyperthyroidism exists

• Subtotal thyroidectomy, removal of a portion of the thyroid gland, is the preferred surgical intervention

Preoperative Management of Thyroidectomy

• Obtain vital signs and weight.

• Assess electrolyte levels.

• Assess for hyperglycemia.

• Instruct the client in how to perform coughing and deep-breathing exercises and how to support the neck in the postoperative period when coughing and moving.

• Administer antithyroid medications, iodides, propranolol, and glucocorticoids as prescribed to prevent the occurrence of thyroid storm

Postoperative Management of Thyroidectomy

• Monitor for respiratory distress.

• Have a tracheotomy set, oxygen, and suction at the bedside.

• Limit client talking, and assess level of hoarseness.

• Avoid neck flexion and stress on the suture line.

• Monitor for laryngeal nerve damage, as evidenced by airway obstruction, dysphonia, high-pitched voice, stridor, dysphagia, and restlessness.

• Monitor for signs of hypocalcemia and tetany, which can be caused by trauma to the parathyroid gland 

• Prepare to administer calcium gluconate as prescribed for tetany.

• Monitor for thyroid storm