Hyperthyroidism & Thyroid disorders Flashcards
what is graves disease
autoimmune cause of hyperthyroidism
what are the symptoms of hyperthyroidism specific to graves disease?
smooth, diffuse goitre
exophthalmos
pretibial myxoedema
what are the generalised symptoms of hyperthyroidism?
weight loss despite increased appetite diarrhoea heat intolerance tachycardia lid lag breathlessness tremors sweatiness
what is the mechanism of graves disease?
anti-TSH receptor antibodies bind to and stimulate TSH receptors
stimulates release of TSH
how does exophthalmos occur in graves?
the antibodies bind to muscles behind the eye
how does pretibial myxoedema occur in graves?
soft tissue growth occurs due to antibody binding
how does graves disease appear on a radioiodine uptake test?
defined black thryoid - pyramidal lobe may be visible
what is plummers disease/toxic nodular goitre?
a benign adenoma of the thyroid, overactive at making thyroxine
normal thryoid cells atrophy
how does toxic nodular goitre appear on a radioactive iodine uptake test?
less uniform uptake - hot nodules
not fully black
atrophy of rest of gland
how does excess thyroxine affect the sympathetic NS?
sensitises b-adrenoreceptors to ambient levels of adrenaline
how does excess thyroxine stimulating the sympathetic NS present?
tachycardia, palpitations, tremors, lid lag
what is thyroid storm?
hyperpyrexia >41c accelerated tachycardia/arrhythmia >170bpm cardiac failure delirium/frank psychosis hepatocellular dysfunction/jaundice
what are the main treatment options for hyperthyroidism?
surgery - thyroidectomy
radioiodine
thionamides (propylthiouracil or carbimazole)
non-specific beta blockers to manage symptoms
what should be done in preparation for thyroidectomy?
potassium iodide for 10 days maximum
beta blockers to relieve symptoms
how do thionamides reduce thyroxine synthesis?
inhibit thyroid peroxidase and hence T3/4 synthesis
biochemical effect - hours but clinical effect - weeks
