Thyroid Flashcards
What does the thyroid gland effect?
Brain function, bone growth, oxygen to organs, sexual maturation, tooth and bone development,
What does the hypothalamus stimulate the release of?
TSH T3 and T4
As T4 levels rise the the TSH levels ____
Fall
What is iodine used for by the body
Synthesis of thyroid hormones
How much iodine is recommended an intake?
150 or for pregnancy or BF 200-220
How does thyroid hormone effect GFR
High thyroid = higher GFR LOWERR = lower GFR
What is cretinism
Severe lack of TSH from iodine deficiency causing retardation, short stature, delayed motor development, protuberant abdomen, coarse hair
At what age should you check TSH of no risk for hypothyroid
60
Where are the T4 and T3 synthesis within the thyroid gland?
Follicular cells of the thyroid gland
What enzyme stimulated by TSH oxidizes iodide to iodine
Thyroid peroxidase
Condensation of two molecules DIT yields what substance?
T4
Which disorder decreases GFR hypo or hyperthyroidism
Hypo
T or F sea salt contains about the same amount of iodine as table salt
False
What is the leading cause of hyperthyroid in all ages?
Graves
What can hyperthyroidism lead to in children?
Cardiomegaly and heart failure
What causes neonatal Graves’ disease?
Maternal IgG antibodies and it resolves when the child is 3-4 months old
What are the symptoms of graves in children?
Hyperactivity, nervousness, emotional lability, ADHD
What two pregnancy hormones can cause increased thyroid levels?
HCG and estrogen
What can hyperthyroidism in pregnancy lead to?
Still birth, miscarriage, or pre eclampsia, premature birth, and low birth weight
How does hyperthyroidism in older adults present?
Atypical, atrial arrhythmias, heart failure, and osteoporosis
What is the second most common cause of hyperthyroidism?
Solitary adenoma or toxic nodule
I’what are signs you can see in hyperthyroidism?
Fast speech, tachycardia, tremor, goiter, a fib, moist skin, thrill or bruit over thyroid
What do labs look like with hyperthyroidism?
Low TSH less than .03, elevated T4 and T3
What is a thyroid antagonist?
Thioamides like methimazole and PTU
What are the tx options for hyperthyroid?
Medicine, radioactive iodine, and surgery,
What is the MOA of thioamides
Prevent thyroid hormone synthesis by inhibiting the thyroid peroxidase catalyzed reactions and blocking the incorporation of iodine into thyroglobulin
When does remission occur in 50% of people on thioamides
12 months
Which thioamide drug is more potent MTZ or PTU
MTZ
How often is PTU dosed?
TID or QID
T or F thioamides are considered safe in breast feeding
T
What are the most common AEs of the thioamides
GI distress, maculopapular rash
Which thioamide is jaundice more common in?
MTZ
Who is more at risk for agranulocytosis on thioamides?
People with reduced bone marrow, older than 40, receiving more than 40mg a day of MTZ.
Why should you monitor a WBC on thioamides?
It can induce a granulocytosis bone marrow suppression
Which drugs interact with thioamides?
Warfarin and heparin, potassium iodide, lithium, and amiodarone
Which med can you NOT take with thioamides
Amiodarone
What is myxedema crisis and what causes it?
Thyroid storm caused by PTU
What should you give for hyperthyroidism if beta blockers are contraindicated in cases like asthma?
Diltiazem
When can radioidine be used in front line therapy?
When patients are not at high risk for hyperthyroidism complications
What is secondary causes of hypothyroidism?
Insufficient thyroid stimulation caused by adenoma, radiation, Cushing, and acromegaly
What labs are affected in adults with hypothyroidism that is not TSH related?
Elevated lipid levels
Which thyroid drug contains T3
Liothyromine sodium
What is the average replacement dose of T4
1.7mcg /kg a day
What decreases the absorption of TSH
PPI and and people who have a had resections of the bowel
What food effect levothyroxine?
Soybean flour, infant formula, cotton seed meal, walnuts, fiber, and calcium foods and juices.
What conditions increases TBG
Pregnancy hepatitis, estrogen, porphyria
