Hyperthyroidism

Question 1

what is the normal range of TSH?

Answer 1

0.3 - 4.5 mU/L

Question 2

what is the normal range of free T4?

Answer 2

9 - 22 pmol/L

Question 3

what is the active thyroid hormone?

Answer 3

T3

Question 4

what treatment can be used prior to an anti-thyroid drug to control symptoms?

Answer 4

beta blockers (mainly propranolol)

Question 5

what is the most serious side-effect of carbimazole?

Answer 5

agranulocytosis

Question 6

what are some potential causes of a thyroid crisis?

Answer 6

acute stressors - trauma, surgery, infection

Question 7

what are the clinical features of thyroid crisis (storm)?

Answer 7

• marked hyperthyroid symptoms
• multi-system compensations (e.g. jaundice, pulmonary oedema, confusion, agitation)

Question 8

what is the management of thyroid crisis?

Answer 8

• supportive management in high dependency unit
• high dose anti-thyroid medication - IV propylthiouracil
• potassium iodide (to inhibit hormone release from the gland)
• cardiac glycoside - IV digoxin
• beta blockers - IV propranolol
• high dose steroids - prednisolone/hydrocortisone
• plasmapheresis if unresponsive to treatment

Question 9

what is the role of high dose steroids in thyroid crisis?

Answer 9

block the conversion of T4 to T3

Question 10

what is subacute (de quervain’s) thyroiditis?

Answer 10

hyperthyroidism followed by hypothyroid phase due to depletion of thyroid hormone from the thyroid gland

hyperthyroidism -> hypothyroidism

Question 11

what are the clinical signs of subacute (de quervain’s) thyroiditis?

Answer 11

• hyperthyroidism
• painful goitre
• malaise
• biochemistry in the early stages consistent with hyperthyroidism
• raised CRP and ESR

Question 12

what is the management of subacute (de quervain’s) thyroiditis?

Answer 12

• NSAIDs + beta blockers
• do not required anti-thyroid medications

Question 13

when does subacute (de quervain’s) thyroiditis resolve?

Answer 13

self-limiting within 6 months - may be some residual hypothyroidism

Question 14

what symptoms would indicate the need to commence anti-thyroid medication?

Answer 14

atrial fibrillation

Question 15

what are the symptoms specific to graves disease?

Answer 15

• exophthalmos
• periorbital oedema
• ophthalmoplediga

Question 16

what is the normal range of total T4?

Answer 16

60 - 150 nmol/L

Question 17

what medication is used to manage women in pregnancy with hyperthyroidism?

Answer 17

propylthiouracil

Question 18

how does propylthiouracil work?

Answer 18

inhibits the thryoperoxidase enzyme which is involved in preparing iodine coupling with thyroglobulin

Question 19

what are the antibiodies found in graves disease?

Answer 19

• TSH-receptor antibodies (found in 90% of graves)
• anti-thyroid peroxidase antibodies (found in 75% of graves)

Question 20

what is postpartum thyroiditis?

Answer 20

• condition occuring in women with autoimmune disease
• hyperthyroid phase in the first 3 months post-pregnancy and then hypothyroid phase

Question 21

what is the management of post-partum thyroiditis?

Answer 21

• watch and wait
• 30% of patients require levothyroxine for 6-12 months

Question 22

biochemical findings in primary hypothyroidism

Answer 22

TSH low + T3 high + T4 high

Question 23

biochemical findings in secondary hyperthyroidism

Answer 23

TSH high + T3 high + T4 high

Question 24

biochemical findings in subclinical hyperthyroidism

Answer 24

TSH low + T3 normal + T4 normal

Question 25

what are the clinical features of hyperthyroidism?

Answer 25

* fine tremor * finger clubbing * sweating * pretibital myxoedema * goitre * thyroid bruit * lid retraction * lid lag * atrial fibrillation * high output heart failure * diarrhoea * muscle wasting * proximal weakness

Question 26

what are the primary causes of hyperthyroidism?

Answer 26

* graves disease * toxic thyroid adenoma * multinodular goitre * silent thyroiditis * de quervain's thyroiditis * radiation

Question 27

what are the secondary causes of hyperthyroidism?

Answer 27

* amiodarone * lithium * TSH producing pituitary adenoma * choriocarcinoma (beta-hCG can activate TSH receptors) * gestational hyperthyroidism * pituitary resistance to thyroxine (i.e. failure of negative feedback) * struma ovarii (ectopic thyroid tissue in ovarian tumours)

Question 28

what are the complications of hyperthyroidism?

Answer 28

* thyroid storm * atrial fibrillation * high output heart failure * osteopenia/osteoporosis * upper airway obstruction due to a large goitre * corneal ulcers/visual loss in graves eye disease

Question 29

what should you screen for if there are signs of lack of compliance?

Answer 29

malabsorption - e.g. coeliac disease

Question 30

what features make grave's disease more moderate and severe?

Answer 30

* lid retraction >2mm * significant soft tissue involvement * exopthalamos >3mm * diplopia * optic neuropathy * corneal breakdown