thyroid gland and thyroid disorders Flashcards
what arteries supply the thyroid gland?
superior thyroid artery (branch of ECA)
inferior thyroid artery (branch of thyrocervical trunk from subclavian artery)
what is the venous drainage of thyroid gland?
superior and middle thyroid veins –> internal jugular vein
inferior thyroid vein –> brachiocephalic vein
what nerves run posterior to thyroid?
recurrent laryngeal nerves
which is the most abundant protein that thyroid hormones bind to?
thyroid-binding globulin
what is the main action of thyroid hormones?
increase basal metabolic rate
1. increase O2 consumption,
2. increase heat production
3. increase Na+/K+ ATPase activity
what are some symptoms of hyperthyroidism?
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)
what is the first-line drug to treat hyperthyroidism and its MOA?
carbimazole
MOA: inhibit thyroid peroxidase –> prevent iodination of tyrosine
which antihyperthyroidism drug is safe for pregnant women in their first trimester?
propylthiouracil (PTU)
what are the specific signs for Graves’ disease?
- Exophthalmos/proptosis (and complications eg. chemosis/conjuctival oedema)
- Pretibial myxoedema
- Finger clubbing (Thyroid acropachy)
- Diffuse goitre with audible bruit
what autoantibodies may be present in hypothyroidism?
thyroglobulin antibodies
thyroid peroxidase antibodies
what is iodine’s main function in therapy?
rapidly inhibit synthesis and release of T3 and T4 (Wolff-chaikoff effect)
which antihyperthyroidism drug reduced peripheral conversion of T4 to T3?
propylthiouracil (PTU)
what do beta blockers do in hyperthyroidism?
- short term symptomatic relief
- hyperthyroid crisis (thyroid storm)
- prepare for thyroidectomy
what is the standard of care drug to give in hypothyroidism and why?
thyroxine (T4) due to its longer half-life compared to triiodothyronine (T3) and oral effectiveness
what are some adverse effects of thyroxine?
osteoporosis (increased T4 –> decreased TSH which has bone-protective functions)
cardiac toxicity (angina, HF, arrhythmias) –> start with small dose in elderly
Reduced levels of T3/4 lead to:
a) increased protein breakdown
b) increased lipolysis
c) increased serum glucose
d) increased glycogen formation
increased glycogen formation
T3/4 hormones increase metabolism rate –> increase fuel sources
what drug is contraindicated in patients with toxic nodular goitre?
amiodarone (anti-arrhythmic drug) –> high levels of iodine –> increased production of thyroid hormone –> worsen hyperthyroid state
Fine tremors in an outstretched hand is typically seen in:
a) acromegaly
b) graves’ disease
c) cushing’s disease
d) addison’s disease
graves’ disease
Thionamides (carbimazole, propylthiouracil) have immediate effects on the level of thyroid hormones in the body. True or false?
False. Full clinical effect only evident after a few weeks
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
B. Fine tremor
