5 - Hyperthyroidism Flashcards
State two common causes of hyperthyroidism.
Graves’ Disease
Plummer’s Disease (toxic nodular goitre)
What type of disease is Graves’? Describe its mechanism.
autoimmune
An autoimmune antibody is produced that behaves like TSH and binds to the TSH receptor thus stimulating thyroid hormone production
What does a thyroid gland look like in Graves’ Disease?
The thyroid gland is smoothly enlarged (goitre) and the whole gland is active
What is the difference between a smooth and a nodular/cystic goitre?
smooth - enlargement of the entire gland
nodular/cystic - enlargements of only part of the gland
What is the direct effect of the antibodies on the eyes of a patient with graves?
lid lag
State some features of Graves’ Disease.
Rapid pulse Warm - heat intolerance Localised pretibial myxoedema Exophthalmos Excitability/nervousness Loss of weight despite increases appetite Muscle wasting Oligomenorrhoea/amenorrhoea Breathlessness, palpitations, tachycardia Sweating Diarrhoea Lid lag
What are the two defining features of Graves’ that are caused by different antibodies than the one that causes the hyperthyroidism?
exophthalmus
pretibial myxoedema
How is graves disease confirmed? What are the tests?
- on palpitation, the gland will feel very diffused and smoothly diffused
- give some radioactive iodine. On a scintigram, the whole gland will be active - ‘cold nodule’
What causes Plummer’s Disease?
a benign adenoma in the thyroid gland
How does Plummer’s disease differ from Graves’?
NOT autoimmune
NO pretibial myxoedema
NO exophthalmos
When examining the neck of someone with Plummer’s what may be seen?
a lump on one side of the neck
What will a technetium or iodine scan of the thyroid show in a patient with Plummer’s Disease?
Will see a hot nodule appear - all the iodine is taken up by one part of the gland
(some patients may have a multinodular goitre)
The rest of the thyroid gland will not be seen because the high thyroxine production will decrease TSH release from the anterior pituitary, the rest of the gland stops producing thyroxine and will shrink
Describe the effects of thyroxine on the sympathetic nervous system.
Thyroxine sensitises beta adrenoceptors to ambient levels of adrenaline and noradrenaline
So you get symptoms of having high adrenaline (tachycardia)
this means that small increasing anxiety can lead to panic attacks
What causes lid lag?
High adrenaline
What is thyroid storm (thyrotoxic crisis)?
give the features
This is a medical emergency (rare) When hyperthyroidism has been left so long that patients have at least two of the following: - Hyperpyrexia - Accelerated tachycardia/arrhythmia - Cardiac failure - Delirium/frank psychosis - Hepatocellular dysfunction, jaundice
What is the treatment for someone with thyroid storm?
any treatment of hyperthyroidism
need prompt and aggressive treatment
How can hyperthyroidism be treated?
- surgery (thyroidectomy)
- radioiodine
- drugs
Give the classes of drugs used in the treatment of hyperthyroidism
Thionamides
Potassium Iodide
Radioiodine
Beta Blockers