Thyroid/Anti-Thyroid Drugs Flashcards
Hormones Secreted by the Thyroid
Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin
Thyroid Hormones and Cardiac Function
Hypothyroid = Bradycardia
Hyperthyroid = Tachycardia
Causes of Hypothyroidism
Insufficient iodine, surgical removal of thyroid, Hashimoto’s disease, insufficient secretion of TSH and thyrotropin-releasing hormone
Levothyroxine (Synthroid)
Synthetic thyroid hormone T4
Replaces in order to achieve normal thyroid levels (euthyroid)
Hormonal content is standardized, and therefore its effects are predictable
Adverse Effects of Levothyroxine
Cardiac dysrhythmias
Myxedema
Extreme hypothyroidism
Cognitive changes, activity intolerance, bradycardia, cardiomegaly, decreased CO, edema, hypoventilation, pleural effusion, hypothermia
Treatment of Myxedema
Replacement drugs, fluid and electrolyte replacement, monitor gas exchange and respiratory status
Causes of Hyperthyroidism
Graves’ disease, multinodular disease, thyroid storm
Signs and Symptoms of Hyperthyroidism
Tremors, heat intolerance, bulging eyes, tachycardia, weight loss, muscle wasting, amenorrhea, exophthalmos
Management of Hyperthyroidism
Radioactive therapy, dexamethasone (antiinflammatory to calm down the thyroid), beta-blockers (slow the heart), surgery
Thyrotoxic Crisis (Thyroid Storm)
Occurs in patients who undergo significant stress (surgery, illness), not triggered by a rise in thyroid hormones
Signs include hyperthermia, severe tachycardia, restlessness, agitation, hypotension, coma, heart failure
Treated with methimazole, beta-blockers, sedation
Antithyroid Drugs
Methimazole (Tapazole) and Propylthiouracil
Used to treat hyperthyroidism and to prevent the surge of thyroid hormones that occurs after surgical treatment or during radioactive iodine treatment for hyperthyroidism
May cause liver and bone marrow toxicity
Methimazole
First-line drug for hyperthyroidism (Graves’ disease, adjunct to radiation therapy, thyroid surgery, thyrotoxic crisis)
Does not cause liver damage or destroy existing stores of thyroid hormone
May take 3-12 weeks for euthyroidism
OBTAIN BASELINE VITAL SIGNS AND WEIGHT, use caution in patients with cardiac disease, hypertension, and pregnant women
Propylthiouracil (PTU)
Inhibits thyroid hormone synthesis; second-line drug for Graves’ disease
Short half-life, full benefits may take 6-12 months to occur
Can cause hypothyroidism, agranulocytosis, severe liver damage
Nursing Implications
Antithyroid Medications are better tolerated with food; give at the same time each day; never stop abruptly; AVOID EATING FOODS HIGH IN IODINE
