Hyperthyroidism Flashcards
definition
hyperthyroidism refers specifically to conditions in which overactivity of the thyroid gland and excess thyroid hormones leads to thyrotoxicosis
thyrotoxicosis definition
thyrotoxicosis is the clinical, physiological and biochemical state arising when tissues are exposed to excess thyroid hormone
hyperthyroidism and thyrotoxicosis are
not the same thing
symptoms of thyrotoxicosis
- palpitations
- atrial fibrillation
- tremor
- sweating
- anxiety, nervousness, irritability, sleep disturbances
- lid retraction
- double vision (diplopia)
- proptosis/ exophthalmus ( specific to graves disease)
- muscle weakness especially in the thighs and upper arms ]
- weight loss despite increased appetite
- heat intolerance
causes of thyrotoxicosis associated with hyperthyroidism subtypes
excessive thyroid stimulation and thyroid nodules with autonomous function
causes of thyrotoxicosis which cause excessive stimulation of the thyroid gland
- graves disease (most common)
- hashitoxicosis
- thyroid cancer (rare cause)
- choriocarcinoma (type of gestational trophoblastic disease which secreted HCG i.e. trophoblast producing cancer occurring during pregnancy)
causes of thyrotoxicosis which cause a thyroid nodule with autonomous function
- toxin solitaire nodule
- toxic multi-nodular goitre
causes of thyrotoxicosis not associated with hyperthyroidism subtypes
thyroid inflammation, exogenous thyroid hormone, ectopic thyroid tissue
causes of thyrotoxicosis caused by thyroid inflammation
- subacute (de quervains) thyroiditis
- post- partum thyroiditis
- drug induced thyroiditis ( amiodarone)
causes of thyrotoxicosis caused by exogenous thyroid hormones
- overtretment of hypothyroidism with levothyroxine
- thyrotoxicosis factitia (self induced thyrotoxicosis)
causes of thyrotoxicosis caused by ectopic thyroid tissue
- metastatic thyroid carcinoma
- struma ovarii (teratoma containing thyroid tissue)
graves disease is the
number one cause of hyperthyroidism
who is graves disease more common in
8x more common in woman with the average age of onset around 20-40 years old
whats is graves disease
autoimmune hyperthyroidism targeting the TSH receptor
symptoms of graves disease
- all the symptoms of thyrotoxicosis and specific graves symptoms:
- graves opthalmopathy
- pretibial myxoedema
- thyroid acropathy
- thyroid bruit
graves opthalmopathy
occurs in 20% of patients with graves disease and is strongly associated with smoking
- exophthalmus (proptosis): abnormal anterior protrusion of the eyeball
- lid retraction
thyroid bruit
occurs only in graves disease and only if there is an extremely large goitre
laboratory investigations for hyperthyroidism
HIGH T3/T3 LOW TSH
- hypercalcaemia and increased ALP due to T3 activating osteoclasts causing increased bone turnover (graves disease is associated with osteoporosis)
- leucopenia (reduced white cell count)
autoantibodies
- TSH receptor autoantibody (most specific to graves)
- thyroglobulin antibody
- thyroid peroxidase antibody ( anti-TPO)
if TSH receptor antibody is negative then
a radioactive iodine uptake test is required, if the antibody is positive then no scan is required, should show confluent increased uptake in graves disease
first line management of graves disease
propranolol+ carbimazole
why is propranolol used in graves disease
used for symptomatic relief of thyrotoxicosis symptoms but does not treat the underling disease
propranolol is a
non-selective beta blockers which blocks beta 1 and beta 2 adrenoreceptors, it thyrotoxicosis is used because the blockage of beta-1- adrenoreceptors in the heart reduces heart rate, contractility and speed of conduction through the AV node and inhibits D101
who is propranolol used with caution
asthmatics because it can cause bronchospasm as it blocks beta-2-adrenoreceptors causing bronchoconstriction