Hyperthyroidism Flashcards
what is the normal range of TSH?
0.3 - 4.5 mU/L
what is the normal range of free T4?
9 - 22 pmol/L
what is the active thyroid hormone?
T3
what treatment can be used prior to an anti-thyroid drug to control symptoms?
beta blockers (mainly propranolol)
what is the most serious side-effect of carbimazole?
agranulocytosis
what are some potential causes of a thyroid crisis?
acute stressors - trauma, surgery, infection
what are the clinical features of thyroid crisis (storm)?
- marked hyperthyroid symptoms
- multi-system compensations (e.g. jaundice, pulmonary oedema, confusion, agitation)
what is the management of thyroid crisis?
- 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
what is the role of high dose steroids in thyroid crisis?
block the conversion of T4 to T3
what is subacute (de quervain’s) thyroiditis?
hyperthyroidism followed by hypothyroid phase due to depletion of thyroid hormone from the thyroid gland
hyperthyroidism -> hypothyroidism
what are the clinical signs of subacute (de quervain’s) thyroiditis?
- hyperthyroidism
- painful goitre
- malaise
- biochemistry in the early stages consistent with hyperthyroidism
- raised CRP and ESR
what is the management of subacute (de quervain’s) thyroiditis?
- NSAIDs + beta blockers
- do not required anti-thyroid medications
when does subacute (de quervain’s) thyroiditis resolve?
self-limiting within 6 months - may be some residual hypothyroidism
what symptoms would indicate the need to commence anti-thyroid medication?
atrial fibrillation
what are the symptoms specific to graves disease?
- exophthalmos
- periorbital oedema
- ophthalmoplediga
what is the normal range of total T4?
60 - 150 nmol/L
what medication is used to manage women in pregnancy with hyperthyroidism?
propylthiouracil
how does propylthiouracil work?
inhibits the thryoperoxidase enzyme which is involved in preparing iodine coupling with thyroglobulin
what are the antibiodies found in graves disease?
- TSH-receptor antibodies (found in 90% of graves)
- anti-thyroid peroxidase antibodies (found in 75% of graves)
what is postpartum thyroiditis?
- condition occuring in women with autoimmune disease
- hyperthyroid phase in the first 3 months post-pregnancy and then hypothyroid phase
what is the management of post-partum thyroiditis?
- watch and wait
- 30% of patients require levothyroxine for 6-12 months
biochemical findings in primary hypothyroidism
TSH low + T3 high + T4 high
biochemical findings in secondary hyperthyroidism
TSH high + T3 high + T4 high
biochemical findings in subclinical hyperthyroidism
TSH low + T3 normal + T4 normal
what are the clinical features of hyperthyroidism?
- 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
what are the primary causes of hyperthyroidism?
- graves disease
- toxic thyroid adenoma
- multinodular goitre
- silent thyroiditis
- de quervain’s thyroiditis
- radiation
what are the secondary causes of hyperthyroidism?
- 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)
what are the complications of hyperthyroidism?
- 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
what should you screen for if there are signs of lack of compliance?
malabsorption - e.g. coeliac disease
what features make grave’s disease more moderate and severe?
- lid retraction >2mm
- significant soft tissue involvement
- exopthalamos >3mm
- diplopia
- optic neuropathy
- corneal breakdown
