Thyroid

Question 1

Function of thyroid

Answer 1

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

Question 2

Thyroid axis

Answer 2

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

Question 3

what regulates uptake of iodine

Answer 3

TSH

comes from diet

Question 4

enzyme that converts T4 to T3

Answer 4

5-DID thyroid deiodinase

Question 5

where are TR receptors found

Answer 5

everywhere except SPLEEN & TESTES
(intranuclear - causes gene modulation)
(TR has 10x greater affinity for T3 - all significant action is via T3)

Question 6

causes of primary hypothyroid

Answer 6

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

Question 7

clinical presentation hypothyroidism

Answer 7

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

Question 8

medical emergency hypothyroidism

Answer 8

myxedema coma:
hypothyroidism 
stupor
hypoventilation
hypothermia
bradycardia
hypertension

Question 9

test for thyroid function

Answer 9

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

Question 10

test for secondary and tertiary hypothyroidism

Answer 10

administer TRH and check TSH levels

TRH(thyrotropin)

Question 11

how do you treat hypothyroidism

Answer 11

levothyroxine
liotrix
liothyronine

Question 12

levothyroxine

Answer 12

synthetic T4
outpatient
slow onset

Question 13

liotrix

Answer 13

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

Question 14

liothyronine

Answer 14

synthetic T3

inpatient

Question 15

causes of hyperthyroid

Answer 15

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

toxic multinodular goiter

toxic nodule

thyroiditis

Question 16

clinical presentation of hyperthyroidism

Answer 16

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

Question 17

medical emergency with hyperthyroidism

Answer 17

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

Question 18

what does iodine supplement do for hyperthyroidism

Answer 18

increased iodine trapping
but reduced organification
i.e 1 week of hypothyroid - but then exacerbates hyperthyroidism

also causes degranulation of mast cells

Question 19

how long does I-131 take

Answer 19

effects of ablation can take 1-3 months

Question 20

what Rx is used for rapid temporary relief of hyperthyroid in thyroid storm; or to normalize levels

Answer 20

propanalol
non selective beta-blocker
blocks excess adrenergic effect

Question 21

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

Answer 21

PTU
propylthiouracil

ADR:
skin rash
bitter taste
liver damage

Question 22

methimazole

Answer 22

inhibits TPO to add iodine to thyroglobulin
hyperthyroidism

ADR:
skin rash
agranulocytosis
aplastic anemia
bitter taste
hepatitis

Question 23

perchlorate

Answer 23

inhibits iodine trapping
hyperthyroidism

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