Thyroid therapy- Hyperthyroidism only (Exam 1) Flashcards
Most common cause of HYPERTHYROIDISM is?
Graves Disease
What causes hyperthyroidism in Graves Disease?
Thyroid stimulation by autoantibodies [TSAb] that mimic stimulation by TSH so i guess to treat graves we need to suppress these pesky autoantibodies (those beeetches)….further reading proved me wrong
There are three treatment options one can try for Graves Disease? what are they?
- Modifying tissue response (symptomatic improvement)
- Interfering with hormone production
- Glandular destruction
What drugs are used for the Modifying tissue response (symptomatic improvement) treatment of graves?
Beta-blockers and corticosteroids and PTU They prevent T4 from being converted to T3
-they act on the peripheral tissue section where T4 is converted to T3
Which drugs are used if you want to treat Graves disease by interfering with hormone production?
- Thioamides
2. Iodides
What methods would you use to treat graves disease using the glandular destruction path?
- Surgery
2. Radioactive iodine
All of the following are adequate test to order when trying to diagnose Hyperthyroidism or thyrotoxicosis except.
A. TSH
B. T4
C. T3
C. T3 do not order this
Which drugs are classified as thioamides?
- Methimazole
2. PTU
True or False: thioamides are best if disease is mild, small gland, or they are a young patient or frequent relapses?
True
What do Thioamides inhibit? how long to deplete T4?
- Thyroid peroxidase (this synthesizes T4/T3)
2. 3-4 weeks to deplete T4
What qualifies as a true hyperthyroid state?
a normal or elevated iodine uptake in the setting of a low TSH. indicating autonomous production of thyroid hormone
If iodine uptake is low and TSH is low, what is causing the hyperthyroid symptoms?
Thyroid hormone excess is due to high release of preformed thyroid hormone
Are thioamides used for thyrotoxicosis due to excess release (low RAI) or excess Production (high RAI).
They are only indicated for thyrotoxicosis due to excess production (graves disease)
What medication can you give to alleviate symptoms of thyrotoxicosis until the thioamides take effect?
beta blockers
Propranolol has advantage of blocking T4—>T3 conversion; metoprolol/atenolol are beta 1 selective, longer t1/2
Between PTU and methimazole, which one is completely absorbed?
Methimazole
PTU is only 50-80%
Methimazole or PTU for pregnancy?
PTU is more protein bound so crosses the placenta less readily and less secretion into breast milk
Between PTU and methimazole which one is given 2-3 times daily and which one is once daily?
PTU is 2-3 times daily (shorter half life)
Methimazole once daily
If you are treating someones thyrotoxicosis with methimazole or PTU, when would you expect clinical resolution? how bout biochemical resolution?
clinical within 2 weeks
biochemical 4-8 weeks
True or false: High doses of PTU will block peripheral conversion of T4 to the more active T3
True
What is the most dangerous adverse reaction when using methimazole or PTU?
agrunulocytosis
Adverse reaction of PTU?
Hepatotoxicity with PTU is rare (1:1000 in children and adults) but severe enough (deaths and liver transplants [3rd leading drug cause]) to raise concerns about routine use
What are three advantages to using methimazole over PTU?
- efficacy at lower doses
- once daily dosing
- lower side effect profile
Super saturated potassium iodide (SSKI) MOA?
- inhibit hormone synthesis (via elevated intracellular [I-])
- inhibit hormone release (via elevated plasma [I-]) through inhibition of thyroglobulin proteolysis
high doses required >6mg daily
do SSKI have a rapid or slow onset?
rapid onset, used in severe thyrotoxicosis- thyroid storm
What are some disadvantages to using SSKI?
- variable effects
- Rapid reversal of inhibitory effect when withdrawn
- Potential to produce new T3- which would worsen hyperthyroidism
Why would you give someone a SSKI or lugols solution prior to surgery?
These medications can decrease size and vascularity of hyperplastic gland (take 7-10 day preop)
How is Radioactive Iodine administered, absorbed (fast or slow), and where does it concentrate?
- orally
- Rapidly
- Concentrates in thyroid
beta radiation causes ______ inflammatory process that destroys parenchyma of gland over a period of weeks to months
Slow
What are the advantages of radioactive iodine?
- Easily administered
- Effectiveness
- Low expense
What are the disadvantages of radioactive iodine?
- Slow onset and time to peak effect (2-6 months to euthyorid state) -10% require second dose
- Radiation thyroiditis via release of preformed T3 causing cardiovascular complications (should give methimazole to decrease synthesis before destroying the gland)
- Causes hypothyroidism
- Can not give to preggos
True or false: 50-60% of patients require thyroid supplementation after surgery (iatrogenic hypothyroidism)
True
What three things do you want to do to treat a thyroid storm?
- Control of symptoms
- inhibition of release of preformed thyroid hormone
- block conversion of T4 to T3
What medication can you use to control the cardiovascular effects of a thyroid storm while also blocking conversion of T4 to T3?
propanolol
What medications can you use to slow the release of hormones during thyroid storm?
- Sodium iodide
2. Potassium iodide
What meds can you use to block the synthesis of hormones?
PTU and methimazole
What are the benefits of hydrocortisone when someone is in a thyroid storm?
- protects against shock
- Blocks conversion of T4 to T3
- may modulate the immune response that lead to exacerbation of thyrotoxicosis
