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Flashcards in Thyroid Deck (23):
1

Function of thyroid

Development, Growth
Regulates BMR - via regulation of metabolism of carbs, lipids, protein, vitamin
Regulates Hormones -

2

Thyroid axis

hypothalmus TRH
anterior pituitary TSH
(-) feedback to thyroid = circulating T4; intrapituitary T3; somatostatin

3

what regulates uptake of iodine

TSH
(comes from diet)

4

enzyme that converts T4 to T3

5-DID thyroid deiodinase

5

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)

6

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

7

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

8

medical emergency hypothyroidism

myxedema coma:
hypothyroidism
stupor
hypoventilation
hypothermia
bradycardia
hypertension

9

test for thyroid function

TSH
free T4
free T3
hashimotos = TPO-antibodies; thyroglobulin-antibodies

10

test for secondary and tertiary hypothyroidism

administer TRH and check TSH levels
TRH(thyrotropin)

11

how do you treat hypothyroidism

levothyroxine
liotrix
liothyronine

12

levothyroxine

synthetic T4
outpatient
slow onset

13

liotrix

T4:T3 mixture (4:1)
outpatient
no advantage over levothyroxine

14

liothyronine

synthetic T3
inpatient

15

causes of hyperthyroid

graves
(B-lymphocytes produce TSH receptor antibodies ... no susceptible to (-) feedback)

toxic multinodular goiter

toxic nodule

thyroiditis

16

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

17

medical emergency with hyperthyroidism

thyroid storm:
uncontrolled hyperthyroidism
extreme fever
tachycardia
vomiting
diarrhea
vascular collapse
confusion

18

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

19

how long does I-131 take

effects of ablation can take 1-3 months

20

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

21

what blocks addition of iodine to to thyroglobulin
and blocks 5-DID
(used in hyperthyroidism)

PTU
propylthiouracil

ADR:
skin rash
bitter taste
liver damage

22

methimazole

inhibits TPO to add iodine to thyroglobulin
hyperthyroidism

ADR:
skin rash
agranulocytosis
aplastic anemia
bitter taste
hepatitis

23

perchlorate

inhibits iodine trapping
hyperthyroidism

ADR:
aplastic anemia + myelosuppression
proteinuria (nephrotic syndrome)
NVF Rash