5) Hyperthyroidism Flashcards
What is wrong in hyperthyroidism?
Excess Thyroxine
2 causes of hyperthyroidism:
Graves disease-antibodies
Plummer’s disease-toxic nodular goitre (adenoma)
Symptoms of hyperthyroidism:
warm skin tachycardia weight loss with increased appetite lid lag family history pretibial myxoedema diarrhoea tremor
How can hyperthyroidism be diagnosed:
Low TSH
High thyroxine levels
Antibodies-high in graves
Examination-smoothly enlarged in graves/lump on one side in plummer’s
-exopthalmos eyes in Graves
Radioactive iodine uptake-whole gland uptake increased in Graves/hot nodule in plummer’s
What sort of diease is Graves?
Autoimmune
What are the 3 types of antibodies involved in Graves disease?
1) TSH receptor=goitre + hyperthyroidism
2) Eyes=exopthalmos
3) Shins=pretibial myxoedma
Why is the whole thyroid gland smoothly enlarged in Graves disease?
Antibody binds to all TSH receptors of all follicular cells=all work harder + grow
How can you distinguish pretibial myxoedma to normal?
Normal=pitting
Pretibial myxoedma=non-pitting
Why are thyroxine levels high in Plummers disease?
Benign overactive adenoma in thyroid gland making thyroxine
What happens to the thyroid gland shape + size in Plummers disease?
One side grows (adenoma) whereas other side shrinks as not being stimulates by TSH (levels are low)
3 key difference between Graves + Plummer’s disease:
Not autoimmune No pretibial myxoedma No exopthalmus Only one side of thyroid gland enlarged Hot nodule in plummers
What is seen during the radioactive iodine test in Plummers disease?
Hot nodule
How does hyperthyroidism affect the SNS?
Thyroxine increases SNS activity
-makes Beta adrenoceptors more sensitive
=skeletal muscle e.g. lid lag/tremor
=heart e.g. tachycardia
What is a thyroid storm?
Extremely high thyroxine levels
-treated with KI
3 ways hyperthyroidism is treated:
Surgery
Drugs
4 types of drugs to treat hyperthyroidism?
1) Thionamides
2) KI
3) Radioiodine
4) Beta-blockers (reduce symptoms)
3 ways thionamides work:
1) inhibit TPO
2) Suppress antibody production in Graves
3) reduce peripheral conversion of T4–>T3
What must be remembered when taking Radioiodine:
To avoid close contact with children/pregnancy/breastfeeding
What is the Wolff-chaikoff effect?
When high levels of KI are taken the thyroid gland shuts down
Why are thionamide effects delayed?
Must wait for T4 stores to run out
What are beta-blockers often used for in hyperthyroidism?
Tor reduce symptoms before other drugs start working
