Hyperthyroidism Flashcards
What is the definition of hyperthyroidism? [2]
an overactive thyroid / resulting in excessive production of thyroid hormone
What is the definition of thyrotoxicosis and what are its 3 mechanisms? [4]
excess thyroid hormone in the blood
- overproduction of thyroid hormone
- leakage of preformed hormone
- ingestion of excess hormone
What are the causes of hyperthyroidism? [5]
- Graves’ disease (most common)
- Toxic multinodular goitre
- Toxic adenoma
- Subacute de Quervain’s thyroiditis
- Drugs - amiodarone
What are the risk factors of Graves’ disease? [6]
- female gender (biggest risk factor)
- genetic (maternal family history)
- infection (E.coli and gram negative bacteria)
- stress
- smoking
- associated autoimmune disease (vitiligo, T1DM, Addison’s)
What is the pathophysiology of Graves’ disease? [5]
serum IgG autoantibodies known as TSH receptor stimulating antibodies (TSHR-Ab) / bind to and activate G-protein-coupled TSH receptors / stimulates thyroid hormone production / excess secretion of thyroid hormones / and hyperplasia of thyroid cells (thyroid enlargement and diffuse goitre)
What are the clinical signs specific to Graves’ disease? [5, 3, 3]
- Graves’ ophthalmopathy - retro-orbital inflammation / swelling of extraocular muscles / exophthalmos / and ophthalmoplegia
- pretibial myxoedema - raised purple-red skin lesions / above the lateral malleoli
- thyroid acropachy - clubbing and painful swelling of fingers and toes / and periosteal reaction in limb bones
How does amiodarone affect the thyroid? [3]
anti-arrhythmic drug / causes hyperthyroidism due to high iodine content / or can cause hypothyroidism by inhibiting the conversion of T4 to T3
What are the symptoms of hyperthyroidism? [7]
- sweating and heat intolerance
- palpitations
- irritability
- tremor
- weight loss and increased appetite
- oligomenorrhoea +/- infertility
- diarrhoea
What are the signs of hyperthyroidism? [8]
- tachycardia/irregular pulse
- fine tremors
- warm moist skin
- palmar erythema
- lid lag and ‘stare’
- goitre/nodules
- thyroid bruit
- Graves’ signs - ophthalmopathy, pretibial myxoedema, thyroid acropachy
What tests can you carry out to diagnose hyperthyroidism? [5]
- thyroid function tests (TFTs)
- thyroid autoantibodies
- TSH receptor stimulating antibodies (TSHR-Ab)
- ultrasound of thyroid
- isotope scan
What would you expect to find from the TFTs? [2]
- low TSH, high T4 and T3
2. in secondary hyperthyroidism (due to pituitary cause), high TSH, T4 and T3
What is diagnostic of Graves’ disease? [1]
increase in TSH-receptor-stimulating antibodies (TSHR-Ab)
What 2 drugs are used for control of hyperthyroid symptoms? [4]
- propranolol - rapid control of symptoms (beta blocker)
2. carbimazole - block thyroid hormone synthesis
What are the side effects of oral carbimazole? [3]
agranulocytosis / decreased white blood cell count / resulting in neutropenia
What are the 2 strategies of giving anti-thyroid drugs? [2]
- titration - carbimazole for 4 weeks / then reduce doses according to TFTs
- block-replace therapy - carbimazole + levothyroxine
