thyroid gland and thyroid disorders

Question 1

what arteries supply the thyroid gland?

Answer 1

superior thyroid artery (branch of ECA)
inferior thyroid artery (branch of thyrocervical trunk from subclavian artery)

Question 2

what is the venous drainage of thyroid gland?

Answer 2

superior and middle thyroid veins –> internal jugular vein
inferior thyroid vein –> brachiocephalic vein

Question 3

what nerves run posterior to thyroid?

Answer 3

recurrent laryngeal nerves

Question 4

which is the most abundant protein that thyroid hormones bind to?

Answer 4

thyroid-binding globulin

Question 5

what is the main action of thyroid hormones?

Answer 5

increase basal metabolic rate
1. increase O2 consumption,
2. increase heat production
3. increase Na+/K+ ATPase activity

Question 6

what are some symptoms of hyperthyroidism?

Answer 6

SWEATING
S - sweating
W - weight loss
E - emotional lability
A - appetite increased
T - tremor/tachycardia
I - intolerance to heat
N - nervousness/neuro (hyper-reflexia)
G - GI issues (diarrhoea), gynae (amenorrhea)

Question 7

what is the first-line drug to treat hyperthyroidism and its MOA?

Answer 7

carbimazole
MOA: inhibit thyroid peroxidase –> prevent iodination of tyrosine

Question 8

which antihyperthyroidism drug is safe for pregnant women in their first trimester?

Answer 8

propylthiouracil (PTU)

Question 9

what are the specific signs for Graves’ disease?

Answer 9

1. Exophthalmos/proptosis (and complications eg. chemosis/conjuctival oedema)
2. Pretibial myxoedema
3. Finger clubbing (Thyroid acropachy)
4. Diffuse goitre with audible bruit

Question 10

what autoantibodies may be present in hypothyroidism?

Answer 10

thyroglobulin antibodies
thyroid peroxidase antibodies

Question 11

what is iodine’s main function in therapy?

Answer 11

rapidly inhibit synthesis and release of T3 and T4 (Wolff-chaikoff effect)

Question 12

which antihyperthyroidism drug reduced peripheral conversion of T4 to T3?

Answer 12

propylthiouracil (PTU)

Question 13

what do beta blockers do in hyperthyroidism?

Answer 13

1. short term symptomatic relief
2. hyperthyroid crisis (thyroid storm)
3. prepare for thyroidectomy

Question 14

what is the standard of care drug to give in hypothyroidism and why?

Answer 14

thyroxine (T4) due to its longer half-life compared to triiodothyronine (T3) and oral effectiveness

Question 15

what are some adverse effects of thyroxine?

Answer 15

osteoporosis (increased T4 –> decreased TSH which has bone-protective functions)
cardiac toxicity (angina, HF, arrhythmias) –> start with small dose in elderly

Question 16

Reduced levels of T3/4 lead to:
a) increased protein breakdown
b) increased lipolysis
c) increased serum glucose
d) increased glycogen formation

Answer 16

increased glycogen formation

T3/4 hormones increase metabolism rate –> increase fuel sources

Question 17

what drug is contraindicated in patients with toxic nodular goitre?

Answer 17

amiodarone (anti-arrhythmic drug) –> high levels of iodine –> increased production of thyroid hormone –> worsen hyperthyroid state

Question 18

Fine tremors in an outstretched hand is typically seen in:
a) acromegaly
b) graves’ disease
c) cushing’s disease
d) addison’s disease

Answer 18

graves’ disease

Question 19

Thionamides (carbimazole, propylthiouracil) have immediate effects on the level of thyroid hormones in the body. True or false?

Answer 19

False. Full clinical effect only evident after a few weeks

Question 20

Jessica Dude, age 47, has been taking thyroxine tablets for hypothyroidism for the last 6 months. She presents to her General Practitioner with palpations and weight loss. If her symptoms are a
side effect of her accidentally taking double her prescribed thyroxine dose, what might the GP expect to find on examination?

A. Exophthalmos
B. Fine tremor
C. Hung‐up reflexes
D. Onycholysis
E. Pretibial myxoedema

Answer 20

B. Fine tremor