Thyroid and Antithyroid drugs Flashcards
What 3 hormones does the thyroid secrete that are essential for regulating metabolism
Thyroxine (T4)
Tri-iodothyronine (T3)
Calcitonin
What does the parathyroid gland do?
Maintains adequate levels of calcium in ECF
What are the functions of the thyroid gland
Regulate protein, lipid, and carb metabolism
Assist with growth and development
Controlhypothalamus (temp)
Effect Cardiovascular, neuromuscular and endocrine systems
What is primary deficiency in thyroid hormones
Abnormality in the thyroid gland
What is secondary deficiency in thyroid hormones
Pituitary doesn’t secrete Thyroid stimulating hormone (TSH)
What is tertiary deficiency in thyroid hormones
Hypothalamus doesn’t secrete thyrotropin-releasing hormone which reduces TSH and thyroid hormone levels
What is congenital hypothyroidism and what is another name for it
Hyposecretion of thyroid hormones during youth
Low metabolic rate, short stature, severely delayed sexual development, possible intellectual disabilities
Cretinism
What is myxedema hypothyroidism
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
What is a goiter
Enlargement of the thyroid gland from overstimulation by elevating levels of TSH
TSH is elevated because of lower amounts of thyroid hormone in circulation
What are common symptoms of hypothyroidism
Cold intolerance
Unintentional weight gain
Depression
Dry, brittle hair and nails
Fatigue
Name a thyroid replacement drug and which hormone does it replace?
Levothyroxine
Synthetic T4 hormone
What is the MOA of levothyroxine
Replaces what the thyroid gland cannot produce (T4)
What are the indications for levothyroxine
Suspected hypothyroidism
Prevention or treatment of goiters
Patients who have had their thyroid removed/destroyed (cancer)
Hypothyroidism
Pregnancy hypothyroidism
What are the contraindications of levothyroxine
MI
Adrenal insufficiency
Hyperthyroidism
What are the adverse effects of levothyroxine
Cardiac dysrhythmia
Tachycardia
Palpitations
Angina
HTN
Insomnia
Tremors
Anxiety
Headache
Diarrhea
Cramps
Menstrual irregularities
Weight loss
Sweating
Heat intolerance
Fever
What are possible interactions with levothyroxine
Enhance warfarin effects
Reduce insulin effects
Increase sensitivity to epinephrine
Cholestyramine, calcium and aluminum bind in GI tract and reduces absorption of drug
Levothyroxine should ________ be discontinued abruptly
Never
Why should levothyroxine be taken in the morning at the same time everyday?
To maintain consistent blood levels and decrease insomnia
What are some causes of hyperthyroidism
Graves disease
Multinodular disease
Plummers diseases
Thyroid storm (from stress or infection, life threatening)
What are symptoms of hyperthyroidism
Increased metabolism
Diarrhea
Flushing
Increased appetite
Muscle weakness
Sleep disorders
Altered menstruation
Fatigue
Palpitations
Nervousness
Heat intolerance
Irritability
What is the purpose of antithyroid drugs and what can they cause
Treat hyperthyroidism
Prevent surge in thyroid hormones
May cause liver and bone marrow toxicity
What are 2 other ways to treat hyperthyroidism
Radioactive iodine works to destroy the thyroid gland (ablation)
Surgery to remove all or part of the thyroid (lifelong thyroid replacement therapy needed)
Name 1 antithyroid drug and how does it work
Propylthiouracil (PTU)
Inhibits conversion of T4 to T3
What are the adverse effects of Propylthiouracil
Leukopenia (manifested as fever, sore throat and lesions)
What should patients on antithyroid meds avoid in their diet?
Foods high in iodine (seafood, soy sauce, tofu, iodized salt)
How long does it take thyroid drugs to take effect
3-4 weeks
