Thyroid/Osteoporosis Flashcards
what 2 medications specifically can induce hypothyroidism
amiodarone (Cordarone)
lithium (Eskalith)
how is primary hypothyroidism confirmed
elevated TSH and low free T4
how is secondary hypothyroidism due to pituitary dysfunction confirmed
loe free T4
low TSH levels
normal TSH
0.5-0.4
Thyroid hormone interactions
drugs that can interfere with absorption such as questran, sucralfate (carafate), aluminum containing antacids, and calcium carbonate
effect of increased estrogen on thyroid
increased estrogen production causes an increased in TBGs which, in turn, causes there to be more T4 in the bound inactive state rather than the free, active state. Will likely need higher dosages of thyroid hormone
drugs that can decrease the affinity of T4 and T3 to TBGs causing a transient increase in free T4 and T3 levels
salicylates
high doses of furosemide
thyroid hormone and coumadin
increases metabolism of vitamin k dependent clotting factors which raises the PT and risk of bleeding
other drugs that alter metabolism of thyroid hormone
phenytoin
carbamazepine (tegretol)
geriatric presentation of hypothyroid
may present with ataxia, paresthesias, and carpal tunnel syndrome
may also present with psychiatric manifestations such as depression and change in sensorium
Causes of hyperthyroidism
graves disease (most common) toxic nodular goiter thyrotoxicosis factita (intentionally take high doses of thyroid hormone)
3 ways to treat hyperthyroidism
antithyroid drugs
radioactive iodine ablation (tx of choice for >40)
surgery
what happens to most patients with graves disease after treatment
they become hypothyroid
antithyroid drugs
methimazole (Tapazole)
propylthiouracil (PTU)
mech of action of antithyroid drugs
inhibits iodine organification
blocks conversion of T4 to T3 in the periphery
what should providers tell patients to report when taking antithyroid drugs
sore throat and fever as this could signify a potentially fatal agranulocytosis
must obtain a CBC and dc drug if WBC low
adjunctive agents used to manage hyperthyroidism
beta-blockers
iodine-containing compounds
lithium
glucocorticoids
geriatric presentation of hyperthyroidism
weakness, dyspnea, anorexia, depression, or constipation
drugs that can be affected when a hyperthyroid patient becomes euthyroid
increased effects of digoxin, metoprolol, and propranolol
treatment of patients with thyroid nodules that are not cancerous
radioactive iodine and surgery
subclinical thyroid disease
elevated TSH with a normal free T4 usually in a patient with no symptoms
subclinical hyperthyroid disease
low TSH with normal T4 and T3
Bone loss after age 30
occurs at about 10% each 10 years
most common fractures in OP
vertebral compression fractures
fractures of distal radius and proximal femur
makeup of long bones
thick outer layer of cortical (dense) bone and a thin inner layer of trabecular (spongy) bone
makeup of short bones
mostly trabecular (spongy) bone with a thin layer of cortical (dense) bone
what causes osteoporosis
an imbalance in bone remodeling that results in greater resorption than formation
resorption-inhibiting drugs
estrogens
bisphosphonates
calcitonin
selective estrogen receptor modulators (SERMs)
recommended dosage of calcium for postmenopausal women
1200-1500mg/day
recommended dosage of vitamin D3 (OP)
800-1000 iu
mech of action of biphosphonates
inhibit bone resorption and increase bone density
bisphosphonates drugs
alendronate (Fosamax)
risedronate (Actonel)
ibandronate (Boniva)
zolendronic acid (Reclast)
contraindications for bisphosphonates
history of esophageal problems, gastritis, or peptic ulcer disease
side effects of bisphosphonates
esophagitis GI (diarrhea and abdominal pain)
bisphosphonate interactions
absorption is decreased when taken with food, calcium, or iron
mech of action of calcitonin
inhibits the action of osteoclasts
not effective at preventing bone loss early in the postmenopausal period but it does increase bone mass in the spine leading to less vertebral compression fractures
adverse events of calcitonin
nasal route can cause rhinitis (inspect nasal mucosa q6mo for ulceration)
SERMs mech of action
mimics the effects of estrogen on bones without replicating the stimulating effects of estrogen on the breast and uterus
SERMs effect on fractures
reduce risk of vertebral fractures but do not affect hip fractures
bonus of SERMs
decrease total cholesterol and LDL cholesterol
SERM drug
raloxifene (Evista)
Hormone modifier used to treat OP
Teriparatide (Forteo)
Mech of action of Forteo (hormone modifier)
stimulates new bone formation in trabecular and cortical bone by stimulating osteoblastic activity over osteoclastic activity
administration of Forteo (teriparatide) hormone modifier
subQ at 20mcg
contraindications to forteo (teriparatide) hormone modifier
pagets disease children previous bone radiation therapy history of skeletal malignancy metabolic bone disease hypercalcemia hyperparathyroidism hx of kidney stones
adverse events of forteo (teriparatide) hormone modifier
may increase calcium levels and increase risk of dig toxicity
RANK ligand inhibitor drug
denosumab (Prolia)
mech of action of denosumab (Prolia RANK ligand inhibitor
targets and binds RANK ligand, inhibiting osteoclast formation, function, and survival, keeping osteoclasts from resorbing bone
dosage of denosumab (Prolia RANK ligand inhibitor
60mg subQ q6mo
contraindication to denosumab (Prolia RANK ligand inhibitor
pregnancy and hypocalcemia
caution with: creat clearance >30, immunocompromised, hx of small bowel excision
adverse effects of denosumab (Prolia RANK ligand inhibitor)
musculoskeletal pain, infection, arthralgia, myalgia, abdominal pain
what must OP patients have in addition to medication
calcium and vitamin D supplementation
1st line therapy for OP
raloxifene or bisphosphonate therapy is used for prevention, bisphophonates are used for treatment
2nd line therapy for OP
calcitonin, hormone modifier, or RANK ligand inhibitor recommended for those who fail to respond to or cannot tolerate 1st line therapy
raloxifene (SERM) contraindications
pregnancy, hx of thromboembolic events
how often should the DEXA scan be performed
every 2 years
