hyperthyroidism Flashcards
what is thyrotoxicosis
excess circulating thyroid hormones (due to any cause, incl hyperthyroidism)
signs and symptoms of hyperthyroidism
- goitre
- hyperactivity
- disturbed sleep
- fatigue
- palpitations
- anxiety
- heat intolerance
- increased appetite with unintentional weight loss
- diarrhoea
which of the following is NOT a sign/symptom of hyperthyroidism
- hyperactivity
- goitre
- heat intolerance
- cold intolerance
- palpitations
- increased appetite and weight loss
cold intolerance is a sign/symptom of HYPOthyroidism
complications of hyperthyroidism
- graves disease
- thyroid storm (thyrotoxic crisis)
- pregnancy complications
- reduced bone mineral density
- HF
- AF
4 risk factors for hyperthyroidism
- smoking
- family history
- co-existent autoimmune conditions
- low iodine intake
which of the following is a risk factor for hyperthyroidism: female patient, 45 years, smoker, suffers from allergic rhinitis, has a diet that mainly consists of animal protein foods and sea vegetables
smoking = risk factor
also more likely in females
what is primary hyperthyroidism
condition arises from thyroid gland itself rather than due to a pituitary or hypothalamic disorder
main cause of primary hyperthyroidism is
graves disease (autoimmune disorder mediated by antibodies that stimulate TSH receptor)
2 other causes of primary hyperthyroidism (apart from graves disease)
- drug induced thyrotoxicosis
- toxic nodular goitre - autonomously functioning thyroid nodules that secrete excess thyroid hormone
primary hyperthyroidism is more common in…
females
primary hyperthyroidism can be classed as
- overt
- subclinical
overt hyperthyroidism
TSH levels below reference and FT4 and/or FT3 levels above reference
subclinical hyperthyroidism
TSH suppressed but FT4 and FT3 within reference
suspect hyperthyroidism if features of graves orbitopathy:
- excessive eye watering
- double vision
- change in visual acuity or colour vision
- eyelid retraction or lid lag
- proptosis (eyes protruding)
assessment of a person with suspected hyperthyroidism - what blood test
- check serum TSH initially
- then measure FT4 and FT3 in the same sample if TSH was suppressed
in amiodarone induced thyroiditis, what type of goitre is present
small goitre
in hyperthyroidism caused by amiodarone, do you need to stop amiodarone
generally yes to reduce iodine load
however long half life so its effect can still persist
treat promptly with antithyroid meds e.g. carbimazole
describe the goitre present in graves disease
thyroid gland is usually diffusely symmetrically enlarged without nodules, and there may be a bruit (a sound)
does subclinical hyperthyroidism tend to be asymptomatic? if there are signs, this tends to be in which population?
yes - clinical symptoms and signs are absent, mild or non-specific. if they are present, they are more likely in younger people
can thyrotoxicosis occur without hyperthyroidism and how can it happen?
yes. usually transient. can occur due to excess intake of levothyroxine or OTC supplements containing thyroid hormone, or from thyroiditis
what is the thyrotoxic phase of postpartum and when does it typically occur and how long for
- thyrotoxic PP typically overs between 1-6 months PP and usually lasts 1-2 months
- happens when the thyroid becomes overactive after birth
checking TSH in suspected hyperthyroidism
- if TSH below normal reference, then measure FT3 and FT4 in the same sample
- overt: low TSH, high FT4 and/or TF3
- subclinical: low TSH, normal FT4 and FT3
a patients lab reports show that they have low TSH, and normal FT4 and FT3. what is the diagnosis
subclinical primary hyperthyroidism
a patients lab reports show that they have low TSH, and high FT4 and/or FT3. what is the diagnosis
overt primary hyperthyroidism
subclinical primary hyperthyroidism - repeating TFTs to confirm diagnosis
- subclinical: low TSH, and normal FT4 and FT3
- repeat after 3 months after initial result or exclude other causes of transiently suppressed TH and to confirm diagnosis
- if on repeat detesting there is persistently low TH and normal FT4 and FT3, diagnosis is confirmed
amiodarone induced hyperthyroidism typically produces the following TFTs results
low TSH, high FT4, raised or normal FT3
which OTC supplement can cause assay interference
OTC biotin can cause falsely low TSH and elevate T4 and T3, indicating hyperthyroidism
non drug treatment options in graves disease of toxic nodular goitre
specialists may consider radioactive iodine or surgery. whilst awaiting these treatments, offer antithyroid drugs to control hyperthyroidism
symptoms of thyroid storm
rapid heartbeat, high temp, high BP, jaundice, loss of consciousness, severe agitation and confusion
what to do if a pt has signs of thyroid storm
medical emergency
emergency admission required
what to do if pituitary or hypothalamic disorder is suspected
refer urgently to endocrinologist
which class of drugs can you consider prescribing whilst awaiting specialist endocrinologist assessment to provide relief of adrenergic symptoms
beta blockers
titrate dose depending on clinical response
helps with adrenergic symptoms e.g. palpitations, tremor, tachycardia, anxiety
when to consider seeking specialist advice about starting antithyroid drugs
- troublesome symptoms despite treatment with BB, or if BB not tolerated or contraindicated
- at risk of complications
- taking drug treatment e.g. amiodarone or lithium - may need liaison between specialistt and endocrinologist
what is the recommended choice of antithyroid drug
carbimazole
before starting antithyroid drugs, check the following
FBC and LFTs
name the 2 antithyroid drugs
carbimazole
propylthiouracil
why is propylthiouracil not 1st line
- small risk of severe liver injury
when can propylthiouracil be prescribed instead of carbimazole
pre-pregnancy
1st trimester
specialist treatment of thyrotoxic crisis
may be used 2nd line if carbimazole not tolerated
antithyroid drugs can only be initiated on
specialist advice
antithyroid drugs are typically used ….. term to achieve ……
short term to achieve euthyroiditis
what does euthyroid mean
normal thyroid gland function
when would antithyroid meds be used long term?
if radioactive iodine treatment or surgery is contraindicated or is declined by the pt