Studied by 2 people3 actions of the thyroid hormones:
stimulate energy use
stimulate the heart
promote growth and development
the 4 thyroid hormone replacements:
levothyroxine (Synthroid)
Liothyronine (cytomel,triostat)
liotrix (euthyroid)
thyroid desiccated (armor thyroid)
4 antithyroid agents:
methimazole (tapazole)
propylthiouracil (PTU)
radioactive Iodine
nonradioactive iodine (lug's solution)
deficient thyroid hormone, lifelong treatment, almost always in adults and sometimes infants
hypothyroidism
symptoms of hypothyroidism:
weight gain, hair loss, intolerance to cold, no appetite, facial and eyelid edema, extreme fatigue, brittle hair and nails, muscle aches and weakness
thyroid agent that treats hypothyroidism, identical to naturally occurring thyroid hormone, given PO, IV form is available, highly protein bound, once per day dosing
Levothyroxine (Synthroid, levoxyl)
When should levothyroxine be administered?
30-60 mins before breakfast
When does levothyroxine reach half life?
1 week
when does levothyroxine reach plateau?
1 month
adverse reactions of levothyroxine:
thyrotoxicosis
osteoporosis
Atrial fibrillation
symptoms of hyperthyroidism
thyrotoxicosis
levothyroxine absorption is decreased by:
calcium, mg
antacids
H2 blockers
sucralfate
cholesterol binding agents
what foods should be avoided when taking levothyroxine:
soy formula
cotton seed meal
high fiber foods
3 drugs that accelerate metabolism of levothyroxine:
phenytoin
carbamazepine
rifampin
levothyroxine increases effects of this anticoag, levothyroxine accelerated the degradation of vitamin K dependent clotting factors
Warfarin
thyroid hormones increase the responsiveness of this drug, use it cautiously, includes epinephrine, dopamine, and dobutamine
Catecholamines
levothyroxine can increase the requirements for both of these drugs
Insulin and digoxin
is levothyroxine safe in pregnancy?
yes, dosage might need to be increased
excessive thyroid hormone secretion, can cause grave's disease, weight loss, jitters, enlarged thyroid, facial flushing
Hyperthyroidism
drug to treat hyperthyroid, first line drug that is recommended unless pregnant, inhibits thyroid hormone synthesis, doesn't do anything to what is already released but will prevent it
Methimazole (tapazole)
What can methimazole cause?
may induce hypothyroidism and can cause agranylocytosis
reduction of granulocytes that's needed to fight infection, most serious and dangerous toxicity
Agranylocytosis
treats hyperthyroidism, second line drug ,inhibits thyroid hormone synthesis and prevents conversion of T4 to T3 in the periphery, can take when pregnant
Propylthiouracil (PTU)
When is propylthiouracil (PTU) preferred?
during thyroid storm/thyrotoxic crisis
used for thyroid cancer or hyperthyroidism, should not use if pregnant/lactating or for children
Radioactive Iodine
a high dose of radioactive Iodine is used for...
thyroid cancer
a low dose dose of radioactive iodine is used for...
hyperthyroidism
used for hyperthyroidism, is a paradoxical inhibition of thyroid hormone secretion, used for short, used in nuclear radiation emergencies, and is an antiseptic
nonradioactive iodine
what may nonradioactive iodine be used before
thyroidectomy
can treat hyperthyroidism, suppresses symptoms by blocking beta receptors
Beta blockers
what type of patent are beta blockers contradicted in?
asthma patients
Note
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