Thyroid and osteoporosis Flashcards
What is the DOC for hypothyroidism?
Levothyroxine sodium (maintenance)
What is the DOC for initial therapy of hypothyroidism?
Liothyronine sodium
What is the DOC for initial tx of hyperthyroidism?
Propranolol (CCB if asthmatic) along with Proprylthiouracil
What are the thioamides? What is their MOA?
Propylthiouracil and Methimazole; decreases peripheral conversion of T4-T3 and blocks the release of T4 from thyroid gland
What are the only two reasons you would not use methimazole?
If pt is allergic or in early PGN
What is the DOC for Grave’s dz?
Methimazole
What are the two primary causes of hyperthyroidism?
Antibodies to TSH receptor (Graves) and a toxic nodular goiter (adenoma)
What are drugs that interact with thyroid replacement drugs? (just read card)
Estrogen and tamoxifen can increase levels of thyroxine-binding globulin Hypothyroid patients may require LARGER DOSES of levothyroxine if an estrogen is added.
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Glucocorticoids and androgens decrease levels of TBG, so have the opposite effect of estrogens (SMALLER DOSES)
Sympathetic stimulants, given together with large doses of thyroxine (this has been done to promote
weight loss), can produce serious and life-threatening cardiotoxicity.
Iodides and lithium: inhibit release or synthesis of thyroid hormones. Amiodarone (antiarrythmic
drug) contains iodide. (negative feedback) NO IODINE
Antacids, sucralfate, cholestyramine, or ferrous sulfate may interfere with absorption of
levothyroxine, which should be taken on an empty stomach. DIFFERENT TIMING OF DOSES
Phenytoin, carbemazepine, or rifampin induce hepatic enzymes, and can increase the metabolism
of levothyroxine, necessitating increased dose. LARGER DOSES
Antidiabetic agents: dose may need to be adjusted if levothyroxine is added or deleted, since thyroid
hormones can affect the diabetic state. This represents a pharmacodynamic interaction and not
necessarily a pharmacokinetic one.
Corticosteroid metabolism can be decreased in hypothyroid patients and increased in hyperthyroid
patients; dose alterations may be required when initiating, changing, or discontinuing levothyroxine
therapy. DISCONTINUE THYROID TX
A patient on methimazole for Graves disease complains to you of a sore throat. What should you look for in a CBC?
Granulocytopenia and agranulocytosis
What can be done to avoid cretinism with use of methimazole in PGN?
LOW DOSE
What can be done to prevent goiter with tx of hyperthyroidism?
addition of T4 (synthroid low dose)
Why is PTU not used very often? What should you monitor with use of it?
Because of black box liver injury warning; monitor LFT and ALT
What is given 7-10 days prior to thyroid surgery to prevent a thyroid storm?
Iodide
What can be used in the case of a radioactive emergency to compete with radioactive iodine to avoid thyroid storm?
Iodide
What are small doses of I131 used for? Large doses?
Diagnostics; to destroy gland in elderly patients who can’t undergo surgery and to kill off remaining tissue post surgery