Hyperthyroidism Flashcards
What is an autoimmune condition that causes hyperthyroidism?
Graves’ Disease
How does Grave’s disease cause hyperthyroidism?
Antibodies bind to and stimulate TSH receptors, cause an overproduction of thyroxine
What is the physical presentation of Grave’s disease?
Smooth diffuse goitre (not tender to touch) including thrill and bruit (hear blood rush), exophthalmos, pretibial myxoedema
increased BMR, body is overactive
How does exophthalmos work?
Antibodies bind to muscles behind the eye, causing eye to protrude forward
How does pretibial myxoedema work?
Antibodies bind to muscles in shin, causing growth of soft tissue
What is the difference between pretibial myxoedema and myxoedema?
Pretibial myxoedema is a sign of hyperthyroidism, myxoedema is an old name for hypothyroidism
How would you image a thyroid to test for Graves’ disease?
Inject radioactive iodine and perform a thyroid scan - should see a uniform smooth uptake of radioactive material to show an enlarged thyroid scan
How many antibodies associated with hyperthyroidism
3
- attached to thyroid gland (goitre)
- attached to eye muscles (exophthalmos)
- attached to shins (pretibial myxoedema)
What is a cancerous condition that causes hyperthyroidism? (benign)
Plummer’s Disease (aka toxic nodular thyroid disease)
How does this disease cause its effects?
Nodule growths (benign adenomas) overproducing thyroxine
Toxic nodular thyroid disease
Toxic nodular goitre,
no exophthalmos,
no pretibial myxoedema
Not an autoimmune disease
How does the shape of the thyroid gland change with toxic nodular goitre and what effect does this have on TSH&T4?
As one side grows (hypertrophy), the other side of the thyroid gland undergoes atrophy. This means a roughly standard amount of TSH&T4 will be released
What are the key features of a thyroid scan in toxic nodular thyroid disease?
A hot spot - one side will take up radioactive iodine, whereas the other side will not (atrophy) and hence will not show up on the scan.
How does thyroxine affect the sympathetic nervous system?
Thyroxine sensitises beta adrenoreceptors to adrenaline and noradrenaline - and has some sympathetic activation.
Therefore, what are some of the sympathetic effects found in hyperthyroidism?
Tachycardia, palpitations, sweating, tremor, lid lag (eye lid delayed in closing because of some sympathetic innervation)
What are the general symptoms of hyperthyroidism?
Weight loss, appetite increase, tiredness, heat intolerance, diarrhoea
What is a thyroid storm?
(thyrotoxic crisis)
When someone with a thyroid condition does not know about it and ignores it for a long time
What heart condition can a thyroid storm lead to?
atrial fibrillation
If a thyroid storm continues to be undetected, what is the percentage of mortality and what are the two main causes of mortality?
50% mortality, either profound hypotension (think tachycardia) or ventricular fibrillation
What are 5 symptoms of a thyroid storm?
requires aggressive treatment
Hyperpyrexia (>41C),
arrhythmia,
cardiac failure,
jaundice,
delirium
What are the 3 treatment types for hyperthyroidism?
Drugs, Radioiodine, Surgery (thyroidectomy)
What are the 4 classes of drugs for hyperthyroidism?
Thionamides, inhibit enzyme sof the thyroid gland
Potassium Iodide, causes negative feedback within thyroid gland (short term)
Radioiodine (capsule)
Non-selective Beta Blockers
Which drugs are anti-thyroid and which are symptom alleviators?
Non-selective beta blockers are symptom alleviators, thionamides/radioiodine/potassium iodide are anti-thyroid
What are two types of thionamides?
Carbimazole,
PTU (propylthiouracil)
