thyroid medications Flashcards
What is the largest endocrine gland in the body?
the thyroid
What 3 hormones does the thyroid produce?
- thyroxine (T4) (converts to T3)
- triidothyronine (T3)
- calcitonin
What hormones are needed for metabolism?
T4 & T3
What does euthyroid mean?
normal thyroid gland function
What is a goiter?
visible enlargemtn of the thyroid gland
What is graves disease?
an antibody mediated autoimmune disease resulting in hyperthyroidism
What is hashimoto’s thyroiditis?
an autoimmune disorder often resulting in hypothyroidism
What is the function of thyroid hormones?
- stimulates metabolic activity & oxygen consumption of cells
- produces heat & thermogenesis
- stimulates carb, fat, & protein metabolism
- increases rate of glucose absorption
- increases erythropoiesis
- mood
- works with growth hormone, insulin & sex steroids to promote growth
in what response is are thyroid hormones required?
normal respiratory response to hypoxia & hypercapnia respiratory drive
In what parts of fetal development are thyroid hormones critical?
neural & skeletal development
What is secretion of t3 & T4 controlled by?
TSH from the anterior pituitary
What does TSH control the rate of?
rate of thyroid hormone release
how does TSH control the rate of thyroid hormone release?
via a negative feedback mechanism
What do levels of thyroid hormone in the blood determine?
release of TSH
excess thyroid hormone in the blood leads to?
inhibition of TSH
low thyroid hormone in the blood leads to?
increase in production of TSH
What stimulates the pituitary to release TSH?
the hypothalamus releasing thyrotropin releasing hormone (TRH)
What are the normal ranges for TSH, T4 & T3?
TSH (0.4 to 4.5)
- less than .4 = hyper/overactive
- more than 4.5 = hypo
T4 (4-11)
T3 (80-180)
What are the sx of hypothyroidism?
fatigue
depression
dry skin
constipation
bradycardia
altered menstruation
weight gain
changes in hair
cold intolerance
cardiac enlargement(in long-standing cases)
Is thyroid hormone production decreased or increased in hypothyroidism?
decreased
What causes hypothyroidism?
- can be primary problem
- can be autoimmune (hashimoto’s)
- can be result of medical tx (radiation; thyroidectomy)
What is the name for sever hypothyroidism?
myxedema
What are the two medications for hypothyroidism?
- levothyroxine
- armour thyroid (desiccated)
What are the 3 medications for hyperthyroidism?
- methimazole
- propylthiouracil
- iodine solutions
What are the brand names of levothyroxine?
- synthroid
- levoxyl
What is levothyroxine?
a synthetic form of T4
levothyroxine has good _____________ & reliability
bioavailability
What is the half life of levothyroxine?
6-7 days
What is the goal of levothyroxine therapy?
to restore the TSH & T4 back to normal
When should levothyroxine be taken?
on an empty stomach before breakfast
Is levothyroxine protein bound?
yes; highly protein bound
What are the side effects of levothyroxine?
usually similar to hyperthyroidism if dose is too high
What is desiccated thyroid also known as?
amour thyroid
What is desiccated thyroid?
is a thyroid extract that comes from animal thyroid gland that have been dried & powdered
what does desiccated thryoid contain?
both T3 & T4
What is the bioavilability of desiccated thyroid?
variable
What are side effects of desiccated thyroid?
- changes in appetite
- chest pain
- diarrhea
What are nursing considerations for hypothyroid medication?
- doses are based on TSH results
- avoid giving calcium containing medications, antacids, or iron supplements at same time
- assess HR prior to giving; if tachycardic may want to consult
- life long medication
- safe for pregnancy
When should blood work be checked when taking hypothyroid medications?
should have TSH checked regulary until dose stabilizes
- levels checked 6-8 weeks after starting & after dose changes
- then anually
- may need to check LFTs & WBCs
What is hyperthyroidism causes by?
increased circulating T3 & T4 which comes from overactive thyroid or excessive thyroid hormone production
hyperthyroidism can be mild or if not treated can lead to ______
death
What is caused by hyper functioning of the thyroid gland?
graves disease (autoimmune disorder)
What is the name for the bulging eyes found in hyperthyroidism?
exopthalmos
What is used to treat exopthalmos?
tepezza
What are the sx of hyperthyroidism?
- anxiety
- restlessness
- diaphoresis
- diarrhea
- N/V
- tachycardia (check for a-fib)
- weight loss
- heat intolerance
- exopthalmos
- changes in menstrual cycle
- insomnia
What does hyperthyroidism depend on?
underlying cause; directed at either
- decreasing thyroid hyperactivity
- preventing complications
What can hyperthyroid tx consist of?
single or combined therapy consisting of:
- anti-thyroid agents
- radioactive iodine
- surgery
What is often the result of hyperthyroid tx?
recurrent hyperthyroidism or permanent hypothyroidism
How do thioamides work?
- lower levels by inhibiting formation of thyroid hormones in the cells
- inhibit conversion of T4 to T3
What do you need to obtain before starting thioamides?
baseline CBC & liver profile
When should thiomides be taken?
should be taken on an empty stomach 30 minutes before eating
How long might it take to see effects of thioamide therapy?
several weeks
What two medications are thioamides?
- methimazole
- propylthiouracil (PTU)
how often is methimazole given?
given once daily
methimazole is the drug of choice unless?
pt is pregnant
Where do side effect of methimazole come from?
thyroid suppression
methimazole causes ______ GI side effects
less
What can cause bone marrow suppression?
methimazole
What does propylthiouracil (PTU) do?
converts T4 to T3
Can PTU be used during pregnancy?
can be used during first trimester of pregnancy then should be stopped
Does PTU have any drug interactions?
yes; several (which ones not stated)
What do you need to monitor in pts taking PTU?
LFTs - increased risk of liver inj
CBC- leukopenia
What are the two types of Iodine used for tx of hyperthyroidism?
- lugol’s solution
- I-131
How long is lugol’s solution used?
used short term
How does Lugol’s solution work?
inhibits release of T3 & T4
What can lugol’s solution cause?
iodinism
What are the sx of iodinism?
- metallic taste
- stomatitis
- sore throat
- hypersensitivity
What is I-131?
radioactive iodine
What is I-131 typically used for?
- thyroid cancer
- thyrotoxicosis
- special cases
Can you do I-131 therapy during pregnancy?
no; contraindicated
What should you avoid when on lugol’s solution?
iodine rich foods (seafood, iodinated salt)
what are side effects of lugol’s solution?
- bitter taste
- tooth staining
What should a pt who is on I-131 therapy do?
increase fluid intake
What kind of precaution should a pt on I-131 therapy be on?
radiation precautions
What is the adjuvant therapy for hyperthyroidism?
beta blockers (propanolol or atenolol)
With what population are beta blockers used as adjuvant therapy for hyperthyroid?
used in older adults when the HR is greater than 90 or may have hx of arrhythmias, HTN or chest pain
When are beta blockers mainly used for hyperthyroid?
used to control sx while waiting for meds to take effect
