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
How can you decrease the risk for a thyroid storm with use of I131?
administration of a thioamide prior to use of I131
What is propranolol’s MOA?
directly inhibits peripheral conversion of T4 to block S&S of hyperthyroidism, use a CCB instead (verapamil)
How does PTH have an effect on vitamin D?
Stimulates production of Vitamin D
How does vit D increase blood Ca2+?
Stimulating collagen synthesis in osteoblasts
Stimulating osteoclast activity through RANKL
↑ Intestinal absorption
↓ Renal excretion
When is calcitonin excreted?
When blood Ca2+ is too high, during PGN when stimulated by estrogen to protect maternal bone
What are the goals of calcitonin?
to decrease osteoclast activity
How is calcitonin administered?
Intranasally or injected. Watch for allergic rhinitis and n/v, respectively
What are the two greatest complications of osteoporosis?
Hip and vertebral fractures
What puts someone at increased risk for osteoporosis?
cortiosteroids post menopausal hyperthyroid alcoholism poor GI absorption
Which SERM can be used for treatment of osteoporosis, esp after HRT during age 50-60?
Raloxifene
Which hormone increases blast activity through RANKL? Which hormone increases clast activity through RANKL?
PTH; Calcitonin
What are two compelling indications for teriparatide use?
since it is recombinant PTH, it stimulates remodeling and bone formation, so it is the ONLY ANABOLIC DRUG for osteoporosis, also useful in hypoparathyroid
How often should teriparatide be injected to stimulate new bone growth?
once or twice daily
What is the number one precaution when using teriparatide?
osteosarcoma potential
Which drug works by acting as an antibody against RANKL receptor to decrease osteoclast activity?
Denosumab; new treatment of choice for severe osteoporosis
What is an absolute CI for denosumab? Relative?
Absolute: hypocalcemia, PGN
Relative: lactation, CKD
What is one major adverse reaction of denosumab?
osteonecrosis of the jaw, many dentists ask if you are on this drug!
What are the IV bisphosphonates?
PAMIdronate, ETIdronate, ZOLEdronic acid, IBANdronate (ETI and IBAN are both)
What are the oralbisphosphonates?
ALENdronate, RISEdronate, ETIdronate, IBANdronate (ETI and IBAN are both)
What is the DOC for osteoporosis?
bisphosphonates
What are indications for giving IV bisphosphonate? Oral?
GERD (must co-administer Ca and Vit D); if they have renal toxicity or hypercalcemia (must take 2 hours before breakfast)
What are contraindications for using oral bisphosphonates?
pts with esophageal disease
