Hypothyroidism

Question 1

what % of hypothyroidism cases are primary vs secondary in etiology

Answer 1

95% primary

5% secondary

Question 2

primary causes of hypothyroidism

Answer 2

iatrogenic–> post ablative for grave’s disease, surgery

thyroiditis

drugs

environmental iodine deficiency

congenital

Question 3

what are the types of thyroiditis that can result in hypothyroidism

Answer 3

hashimotos

post partum

irradiation

Question 4

what drugs can cause hypothyroidism

Answer 4

lithium

ASA

PTU

Question 5

what are some congenital causes of hypothyroidism

Answer 5

thyroid agenesis

thyroid dysgenesis

Question 6

what are secondary causes of hypothyroidism

Answer 6

pituitary –> Sheehan’s syndrome, tumours

hypothalamic hypothyroidism

Question 7

what are major things on history suggestive of hypothyroidism, or that you should ask about specifically if you suspect hypothyroidism

Answer 7

1. fatigue–> do you feel tired all the time
2. cold intolerance–> more or fewer clothes needed than rest of family?
3. hoarseness–> any voice changes?
4. depression
5. weight gain
6. amenorrhea

Question 8

general things to ask on history for hypothyroidism

Answer 8

fatigue
cold intolerance
slowness
hoarseness
depression
iodine deficiency

Question 9

HEENT things to ask on history for hypothyroidism

Answer 9

eye changes, diplopia

neck mass

Question 10

CVS things to ask on history for hypothyroidism

Answer 10

bradycardia

Question 11

GI things to ask on history for hypothyroidism

Answer 11

anorexia–> appetite?
weight gain
constipation

Question 12

GU things to ask on history for hypothyroidism

Answer 12

menorrhagia, amenorrhea, anovulatory cycles

Question 13

neuro/MSK things to ask on history for hypothyroidism

Answer 13

paresthesias

muscle cramps or wasting

Question 14

derm things to ask on history for hypothyroidism

Answer 14

dry skin, hair loss, thinned eyebrows, puffiness of face

Question 15

focused physical exam for hypothyroidism

Answer 15

general–> psychomotor depression, hoarseness

vitals–> bradycardia, diastolic HTN

skin–> color, moisture

hair–> fine or thick hair, loss of eyebrow hair in the outer third especially

eyes–> lid lag, proptosis, periorbital edema

compete thyroid exam

neck–> cervical LAD

CVS–> AF, tachy, brady

MSK–> fine motor tremor, proximal weakness, pretibial edema, delayed relaxation phase of reflexes

Question 16

what constitutes a complete thyroid exam

Answer 16

IAPP

inspect, auscultate, palpate, percuss

goiter

nodule

make them swallow

Question 17

how are reflexes changed in hypothyroidism

Answer 17

delayed relaxation phase

Question 18

what is the earliest and most sensitive indication of hypothyroidism

Answer 18

increased serum TSH

Question 19

what other lab tests should be ordered, other than TSH, to work up hypothyroidism

Answer 19

free T4, T3

anti-TPO and anti-thyroglobulin antibodies (for hashimotos)

thyroid u/s

thyroid scan with radioactive iodine uptake

Question 20

management of hypothyroidism

Answer 20

T4 (thyroid hormone) replacement with levothyroxine (synthroid)

starting dose 25-50 mcg/day

increase over 2 months

maintenance dose 75-150 mcg/day

Question 21

what is the dose of synthroid post total thyroidectomy

Answer 21

1.7 mcg/mg

Question 22

how do you treat myedema coma

Answer 22

rapid treatment

ABC, O2, IV

levothyroxine 500 mcg bolus then 100 mcg IV daily

hydrocortisone 100 mcg IV q6h

warming blankets