7 - Thyroid Disorders Flashcards
What are two features of cretinism?
- stunted growth
- low IQ
What is the anatomy of the thyroid gland?
- shield-shaped
- 4 lobes
- at back of tongue at back of neck
- 4 parathyroid glands embedded
- left recurrent laryngeal nerve runs close to thyroid (vocal cord supply)
What are the 4 lobes of the thyroid?
- right (biggest)
- left
- pyramidal
- isthmus
What is the embryology of the thyroid?
- midline outpouching of floor of pharynx
- origin at base of tongue
- forms thyroglossal duct which elongates down neck and divides into 2 lobes
- final position by week 7
- duct disappears when in position and leaves foramen caecum
- thyroid gland then develops
What is agenesis?
complete absence of thyroid
What is a cretin?
an individual with irreversible brain damage caused by lack of thyroxine
What are some issues with the development of the thyroid?
- incomplete descent (between base of tongue and trachea)
- thyroglossal cyst may form (segment of duct persists and presents as lump years later)
What is primary hypothyroidism (myxoedema)?
- primary thyroid failure
- caused by autoimmune damage to thyroid or through accidental removal in surgery
- thyroxine levels decline
- TSH levels climb
What are the features of myxoedema?
- deepening voice
- depression and tiredness
- cold intolerance
- weight gain with reduced appetite
- constipation
- bradycardia
- eventual myxoedema coma
What is the treatment for myxoedema?
- replace thyroxine with 100mg tablet daily
- TSH monitored and dose adjusted accordingly
What is an overactive thyroid gland?
- makes too much thyroxine and TSH levels fall to zero
- hyperthyroidism/thyrotoxicosis
What are the internal features of an overactive thyroid gland?
- raised basal metabolic rate
- raised temperature
- calories burnt up and weight loss
- increased heart rate
What are the external symptoms of an overactive thyroid gland?
- myopathy
- mood swings
- hot in all weather
- diarrhoea
- increased appetite with weight loss
- hand tremors
- palpitations
- sore eyes
What is graves’ disease and its features?
- whole thyroid gland is smoothly enlarged and overactive
- autoimmune
- antibodies bind to and stimulate TSH receptor in thyroid
- causes hyperthyroidism
- other antibodies bind to muscles behind eye and cause exopthalamos or stimulate growth of shins to cause hypertrophy
What is pretibial myxoedema?
- growth of soft tissue on shins
