Thyroid and Antithyroid agents Flashcards
What does the hypothalamus release to stimulate the thyroid? what does it act on?
thyrotropin releasing hormone
Pituitary
What does the pituitary release to stimulate the thyroid?
thyroid stimulating hormone
Does T3 and T4 stimulate the hypothalamus and pituitary?
No negative inhibition
What are the 3 main actions of thyroid hormones?
- increase basal metabolic rate
- increase heart rate and cardiac output
- stimulate protein synthesis
[also stim carb metabolism and lipolysis, REDUCE insulin sensitivity]
What carries thyroxine and triodothyronine in the blood?
thyroxine binding globulin
What inhibits the release of T3 and T4?
iodide
Does MMI effect peripheral conversion of T4 to T3?
No, just PTU although they both do the oxidation , iodination and coupling inhibition
In Grave’s disease, are the hypothalamus and the pituitary hyperactive?
NO! they are actually inhibited by negative feedback of T3 and T4. low TSH
What is the target for treatment in hyperthyroidism?
decrease synthesis and or release of thyroid hormones
How do we administer PTU or MMI? onset of action?
- Orally
2. slow (weeks) takes time to deplete thyroid hormone stores
T-F–PTU works faster than MMI, but is less potent and has a longer duration of action?
False- shorter duration
T-F–preganant women with hyperthyroidism should be treated with MMI in the 1st trimester? What about when nursing?
False…PTU
Both can be used when nursing
T-F-PTU and MMI starts with low doses and gradually progresses? how long is treatment?
False-opposite is true
Treatments are long- 12-18 months
What is incidence of relapse from PTU and MMI treatment?
50%
What is time course of action for iodide treatment
fast but the effect is transient–rarely used as a sole therapy
When should we never use 3-121 generic iodion?
pregnant women or nursing mothers
After thyroidectomy, what is required in 80-90% of cases?
replacement therapy to treat resulting hypothyroidism
Why are beta-adrenergic antagonists used in hyperthyroidism?
used to alleviate symptoms associated with increased CV activity
What sky rockets in primary hypothyroidism, (HASHIMOTOs disease)?
- thyrotropin releasing hormone TRH
2. Thyroid stimulating hormone TSH
What lacks in secondary hypothyroidism? Tertiary hypothyroidism?
- TSH
2. TRH
what does perchlorate cause as a side effect? iodine deficiency?
hypothyroidism for both
In hypothyroidism do we see hyperthermia or hypothermia?
hypothermia
along with drowsiness, sluggishness, mental/growth retardation
What is severe hypothyroidism also known as?
myxedema
What is the extreme expression of severe long lasting hypothyroidism? how do we treat?
myxedema coma- treated with IV T3 in addition to emergency procedures
Do synthetic analogs of T3 and or T4 that act as agonists of the thyroid hormone receptor exist?
not yet available
How long is treatment of hypothyroidism?
life long
How much more hormone do children require than adults in treatment of hypothyroidism?
10x more /kg
Is T3 or T4 more potent? longer half life? higher oral absorption? more expensive?
T3
T4
T3
T3
Who should we be careful in treating with thyroid hormones T3 and T4?
1 patients with cardiac disease
2. pregnant women (they require 30-50% more hormone
