Thyroid Pharm Flashcards
Who is most likely to suffer from a thyroid disorder: men or women; young or old?
Older women
What is the precursor molecule of thyroid hormones?
tyrosine
A defect in the sodium-iodide transporter would lead to which thyroid disorder?
Hypothyroidism
What enzyme iodinates thyroglobulin?
thyroid peroxidase
Thyroxin is bound to what protein in the blood?
Thyroxin-binding globulin (TBG)
Is T3 of T4 the ligand for the thyroid hormone receptor?
T3
Symptoms of hypothyroidism
fatigue, weight gain, sensitivity to cold, goiter, muscle weakenss, constipation
What is Hashimoto’s thyroiditis?
Autoimmune disease with production of antibodies against thyroid peroxidase, Na-iodide symporter, thyroglobulin, or TSH receptor
What is myxedema?
severe form of hypothyroidism mostly in adult women
What is cretinism?
Infancy hypothyroidism leading to mental retardation and dwarfism
What are the two main goals of thyroid hormone replacement therapy?
(1) to replace the function of the thyroid gland; (2) to prevent further growth of thyroid tissue
Synthetic thyroid hormones (3)
levothyroxine sodium (T4); liothyronine sodium (T3); Liotrix (T3+T4)
Which synthetic thyroid hormone drug is the preferred treatment for hypothyroidism and why?
Levothyroxine sodium (T4); longer half life and can be effectively converted to T3 in peripheral tissues
How long does is take for the peak therapeutic effect of levothyroxine sodium?
3-4 weeks
What are the benefits to using liothyronine sodium?
IV formulation can be used in acute emergencies; reaches peak levels in 2-4 hours after oral administration; eliminated rapidly (half-life= 1 day)
What are the disadvantages to using liothyronine sodium?
less stable, more costly, transient high levels of T3 in the serum
What are some precautions to consider when giving someone hormone replacement therapy?
If they have cardiovascular disease or are pregnant (cretinism)
Symptoms of hyperthyroidism
heart palpitations, weight loss, nervousness, sweating, diarrhea, insomnia
Number one cause of hyperthyroidism
Grave’s disease: autoimmune disease consisting of thyroid-stimulating antibodies that activate thyrotropin receptor on thyroid cells
Other causes of hyperthyroidism
nodular goiter, thyroiditis, thyroid cancer
Typical lab findings in hyperthyroidism
TSH decreased; T3+T4 increased
4 hyperthyroid treatment strategies
(1) subtotal thyroidectomy + T4; (2) irradiate thyroid + T4; (3) inhibit thyroid peroxidase; (4) interfere with thyroid hormone activation of symp nervous system
3 drugs that inhibit thyroid peroxidase (antithyroids)
Propilthiouracil, methimazole, carbimazole
Which antithyroid drug has an active metabolite?
Carbimazole’s active metabolite is Methimazole
Severe side effects of antithyroid drugs
agranulocytosis, hepatitis, lupus-like syndrome
Which antithyroid drug, Propylthiouracil or Methimazole, has a lesser chance of agranulocytosis and a shorter half-life?
Methimazole
Which antithyroid drug has a high risk of transferring across the placenta in pregnant women?
Methimazole
How long does it take for the effects of radioactive iodine therapy to be seen?
4 weeks
What is the indication for Radioiodine therapy?
Relapsed hyperthyroidism after antithyroid drug therapy
What is the contraindication to radioiodine therapy?
Pregnancy-radiation can effect fetus; also passes in breast milk so should be not given to women breast-feeding
What is the main side effect of radioiodine therapy?
hypothyroidism
When are beta-adrenergic drugs used?
to control symptoms of hyperthyroidism such as anxiety, palpitations, tremor
