Thyroid & Antithyroid drugs Flashcards
Thyroid Gland
main role
3 hormones
Secretes three hormones essential for proper regulation of metabolism:
Thyroxine (T4)
Tri-iodothyronine (T3)
Calcitonin
Thyroid Gland is located near which gland?
function of this gland?
Located near the parathyroid gland, which is responsible for maintaining adequate levels of calcium in the extracellular fluid
Four Functions of the Thyroid Gland
Regulate protein, lipid and carbohydrate metabolism
Assist with normal growth & development
Control thermoregulatory centre
Effect cardiovascular, neuromuscular, and endocrine systems
Hypothyroidism:
Primary
Primary: abnormality in the thyroid gland itself
Hypothyroidism:
Secondary
Secondary: results when the pituitary gland is dysfunctional and does not secrete thyroid-stimulating hormone (TSH)
Hypothyroidism:
Tertiary
Tertiary: results when the hypothalamus gland does not secrete thyrotropin-releasing hormone, which, in turn, reduces TSH and thyroid hormone levels
Congenital hypothyroidism
Hyposecretion of thyroid hormone during youth
Low metabolic rate, short stature, severely delayed sexual development, possible intellectual disabilities
Myxedema
Hyposecretion of thyroid hormone during adulthood
Decreased metabolic rate, loss of mental and physical stamina, weight gain, loss of hair, firm edema, yellow dullness of the skin
Goiter
Enlargement of the thyroid gland
Results from overstimulation due to increased levels of thyroid-stimulating hormone (TSH)
TSH is increased because there is little or no thyroid hormone in circulation.
Hypothyroidism symptoms
Cold intolerance
Unintentional weight gain
Depression
Dry, brittle hair and nails
Fatigue
Late clinical manifestations:
Brdaycardia
Weight gain
Decreased LOC
Thickened skin
Cardiac complications
Thyroid Replacement Drugs
levothyroxine (Synthroid®, Eltroxin®, Euthyrox®)
—-Synthetic thyroid hormone T4
Thyroid drugs action?
replace what the thyroid gland cannot produce to achieve normal thyroid levels (euthyroid).
work the same way as endogenous thyroid hormones.
Thyroid gland Indications
Used to replace what the thyroid gland itself cannot produce to achieve euthyroid condition (levothyroxine)
Indicated when there is a diagnosis of suspected hyperthyroidism (as in a thyroid-stimulating hormone–suppression test)
Used for prevention or treatment of various types of goiters
Replacement hormonal therapy for patients whose thyroid glands have been surgically removed or destroyed by radioactive iodine in the treatment of thyroid cancer or hyperthyroidism
Hypothyroidism of pregnancy
Thyroid drugs Contraindications
MI, Adrenal insufficiency, hyperthyroidism
Thyroid drugs Adverse Effects
Cardiac dysrhythmia is the most significant adverse effect.
May also cause (like hyperthyroidism):
Tachycardia, palpitations, angina, dysrhythmias, hypertension, insomnia, tremors, headache, anxiety, nausea, diarrhea, cramps, menstrual irregularities, weight loss, sweating, heat intolerance, fever, others
Thyroid drugs Interactions
Enhance warfarin so reduce dose
Reduce efficacy of digoxin and insulin so increased dosage may be needed
Increased sensitivity to epinephrine
Cholestyramine, calcium and aluminum bind in GI tract and reduce absorption both drugs
Thyroid drug important facts
Never discontinue abruptly
Give same time each day to maintain consistent blood levels
–Take in am to decrease insomnia
DO NOT INTERCHANGE BRANDS!
—Brands are not equivalent in dosing and can destabilize treatment
Hyperthyroidism: Excessive Thyroid Hormones is caused by?
Graves’ disease
Multinodular disease
Plummer’s disease (rare)
–Also called toxic nodular disease
Thyroid storm (induced by stress or infection)
–Severe and potentially life-threatening
Hyperthyroidism
define
symptoms
Affects multiple body systems, resulting in an overall increase in metabolism:
Diarrhea
Flushing
Increased appetite
Muscle weakness
Sleep disorders
Altered menstrual flow
Fatigue
Palpitations
Nervousness
Heat intolerance
Irritability
Antithyroid Drugs
used to treat?
may cause____ &_____ toxicity?
Used to treat hyperthyroidism and to prevent the surge in thyroid hormones that occurs after surgical treatment or during radioactive iodine treatment for hyperthyroidism
May cause liver and bone marrow toxicity
Treatment of Hyperthyroidism
Radioactive iodine:
Surgery:
Radioactive iodine (I131): works by destroying the thyroid gland “ablation”
Surgery to remove all or part of the thyroid gland
–Lifelong thyroid hormone replacement will be needed.
Antithyroid drugs: thioamide derivatives
Propylthiouracil (PTU)
inhibition of iodine impedes thyroid hormone production
Propylthiouracil inhibits conversion of T4 to T3
Nursing Implications
Assess for drug allergies, contraindications, and potential drug interactions.
Obtain baseline vital signs and weight.
Cautious use is advised for those with cardiac disease or hypertension and for pregnant women.
During pregnancy, treatment for hypothyroidism should continue.
Fetal growth may be retarded if maternal hypothyroidism is untreated during pregnancy.
–Adjust dosage every 4 weeks to keep thyroid-stimulating hormone at the lower end of the normal range.
Teach patients to take thyroid drugs once daily in the morning to decrease the likelihood of insomnia if taken later in the day.
Teach patients to take the medications at the same time every day and not to switch brands without primary care provider approval.
Teach patients to report any unusual symptoms, chest pain, or heart palpitations.
Teach patients not to take over-the-counter medications or herbal remedies without primary care provider approval.
Teach patients that therapeutic effects may take several weeks to occur.
Teach patients the importance of alerting health care providers of thyroid medication use.
–May enhance activity of anticoagulants
–Patients with diabetes may need increased dosages of hypoglycemic medications.
–May decrease serum digoxin levels
Antithyroid medications nursing interventions
Better tolerated when given with food
Give at the same time each day to maintain consistent blood levels.
Never stop these medications abruptly.
Avoid the patient’s consumption of foods high in iodine (seafood, soy sauce, tofu, iodized salt).
Monitor therapeutic response.
Thyroid drugs: decreased symptoms of hypothyroidism, improved energy levels, improved mental and physical stamina
Antithyroid drugs: no evidence of hyperthyroidism
Watch for and monitor adverse effects of both drugs.
Thyroid drugs: cardiac dysrhythmia
Antithyroid drugs: leukopenia (manifested as fever, sore throat, lesions)
Nursing Consideration Highlights
Monitor vital signs
Baseline TSH, T4, T3
Watching for signs of either HYPER or HYPO
It may take 3-4 weeks for thyroid drugs to take effect
Regular blood level monitoring required
Brand changes are not bioequivalent so not recommended to change brands
