Thyroid Flashcards
(23 cards)
Function of thyroid
Development, Growth
Regulates BMR - via regulation of metabolism of carbs, lipids, protein, vitamin
Regulates Hormones -
Thyroid axis
hypothalmus TRH
anterior pituitary TSH
(-) feedback to thyroid = circulating T4; intrapituitary T3; somatostatin
what regulates uptake of iodine
TSH
comes from diet
enzyme that converts T4 to T3
5-DID thyroid deiodinase
where are TR receptors found
everywhere except SPLEEN & TESTES
(intranuclear - causes gene modulation)
(TR has 10x greater affinity for T3 - all significant action is via T3)
causes of primary hypothyroid
thyroidectomy / ablation subacute thyroiditis infiltrative diseases - sclerosis; amyloid iodine deficiency congenital autoimmune - hashimoto's
Rx:
amiodarone (anti-arrhythmic)
lithium (bipolar)
nitroprusside (anti-angina)
secondary:
pituitary
tertiary:
hypothalmus
clinical presentation hypothyroidism
GENERAL: fatigue cold intolerance mental slowing physical slowing enlarged tongue
CVS:
bradycardia
artherosclerosis
pericardial effusion
GI:
constipation
weight gain
NEURO:
paresthesia
slow speech
muscle cramps
GU:
menorrhagia
ammenorrhea
anovulatory cycles
DERM: puffy face periorbital edema cool, dry, rough skin coarse hair thinned eyebrows
HEME:
anemia
medical emergency hypothyroidism
myxedema coma: hypothyroidism stupor hypoventilation hypothermia bradycardia hypertension
test for thyroid function
TSH
free T4
free T3
hashimotos = TPO-antibodies; thyroglobulin-antibodies
test for secondary and tertiary hypothyroidism
administer TRH and check TSH levels
TRH(thyrotropin)
how do you treat hypothyroidism
levothyroxine
liotrix
liothyronine
levothyroxine
synthetic T4
outpatient
slow onset
liotrix
T4:T3 mixture (4:1)
outpatient
no advantage over levothyroxine
liothyronine
synthetic T3
inpatient
causes of hyperthyroid
graves
(B-lymphocytes produce TSH receptor antibodies … no susceptible to (-) feedback)
toxic multinodular goiter
toxic nodule
thyroiditis
clinical presentation of hyperthyroidism
GENERAL: fatigue heat intolerance irritability fine tremor
CVS:
tachycardia
atrial fib
palpitations
GI:
weight loss w/increased appetite
thirst
hyperdefecation
NEURO:
proximal muscle weakness
GU:
scant menses
decreased fertility
DERM:
fine hair
skin moist, warm, vitiligo, soft nails, onycholysis
HEME: splenomegaly lymphadenopathy lymphocytosis leukopenia
medical emergency with hyperthyroidism
thyroid storm: uncontrolled hyperthyroidism extreme fever tachycardia vomiting diarrhea vascular collapse confusion
what does iodine supplement do for hyperthyroidism
increased iodine trapping
but reduced organification
i.e 1 week of hypothyroid - but then exacerbates hyperthyroidism
also causes degranulation of mast cells
how long does I-131 take
effects of ablation can take 1-3 months
what Rx is used for rapid temporary relief of hyperthyroid in thyroid storm; or to normalize levels
propanalol
non selective beta-blocker
blocks excess adrenergic effect
what blocks addition of iodine to to thyroglobulin
and blocks 5-DID
(used in hyperthyroidism)
PTU
propylthiouracil
ADR:
skin rash
bitter taste
liver damage
methimazole
inhibits TPO to add iodine to thyroglobulin
hyperthyroidism
ADR: skin rash agranulocytosis aplastic anemia bitter taste hepatitis
perchlorate
inhibits iodine trapping
hyperthyroidism
ADR:
aplastic anemia + myelosuppression
proteinuria (nephrotic syndrome)
NVF Rash
