Thyroid disorders Flashcards
what shape is the thyroid gland
shield
where is the thyroid gland
the neck
What is the origin of the thyroid?
back of the tongue
outpouching forms a duct which elongates down - thyroglossal duct
migrates down neck and divides into 2 lobes
What is the foramen caecum?
dimple at back of tongue - disappearing thyroglossal duct
What is the adult thyroid weight?
20g
How many lobes are there? Which is the largest?
4 lobes
right is the largest
What glands are found embedded within the thyroid?
parathyroid glands
They are functionally distinct from the thyroid gland
What important nerve runs very close to the thyroid gland and what does it supply?
left recurrent laryngeal nerve
supplies the vocal cord
List the three problems that can occur with development of the thyroid.
Agenesis - complete absence
incomplete descent - from base of tongue to trachea
thyroglossal cyst - segment of duct persists and presents as a lump years later
What term is used to describe an individual who has irreversible brain damage caused by lack of thyroxine in foetal and neonatal life?
Cretin
Thyroid disease affects approximately 5% of the population. Is it more common in males or females?
females
describe primary hypothyroidism (myxoedema)
Primary thyroid failure
autoimmune damage to thyroid/operation
thyroxine levels decline
TSH levels climb
What biochemical findings occur in an individual with primary hypothyroidism?
Thyroxine levels decline
TSH levels climb
List the features of primary hypothyroidism.
deepening voice depression and tiredness cold intolerance weight gain with reduced appetite constipation bradycardia eventual myxoedema coma diminished perspiration prolonged recovery from reflex
Why is treatment of hypothyroidism essential?
patients will die otherwise
they will perform poorly
cholesterol goes up - causing death from heart attacks and strokes
What is the treatment of hypothyroidism?
replace thyroxine - one tablet, 100mg on average, daily
monitor TSH and adjust dose until TSH is normal
What biochemical findings occur in an individual with hyperthyroidism?
TSH levels fall to 0 raised basal metabolic rate Raised temperature burn up calories and lose weight increased heart rate every cell in the body speeds up make too much thyroxine (immune system tell thyroid gland to make more thyroxin)
List the features of an overactive thyroid gland.
myopathy mood swings diarrhoea increased appetite but weight loss tremor of hands palpations sore eyes goitre
features of hyperthyroidism
Tremor - over active all adrenaline affect muscles palpatations hot weight loss mood swings sore eyes - immune problem with thyroid goitre myopathy diarrhoa
what is the blood supply to the thyroid like
the thyroid is very vascular
what are the features of the thyroid gland
pyramidal lobe
isthamus
right and left lobe
parathyroid glands
Is the thyroid gland essential to life
yes
size of each lobe
4x2.5x2.5cm
what is the origin of the pyramidal lobe
it is left from the descent from the tongue
what is an aberrant parathyroid gland
a parathyroid gland that is in the wrong place
if it is malignant you need to find it and remove it otherwise calcium metabolism is messed up
what is thyroid cartilage
it is what you can feel
what is the problem with a lingual thyroid
it hasn’t grown down at all
can’t remove it because you need the thyroid to survive
without thyroxin the brain doesn’t develop properly
features of cretinism
slow mentation
slow growth
small height
how do you prevent cretinism
screening heel prick test measure TSH at the same time as Guthrie test for phenylketonuria given thyroxine immediately if TSH high
what is the colloid
where thyroxin is stored and it contains thyroglobin
what does thyrocine binding globulin do
bonds 75% of thyroxine in the circulation
only 1% of thyroxine is free
whereas thyroglobin is inside the thyroid gland only
what is the role of the thyroid gland
responsible for the synthesis, storage and secretion of thyroid hormones
what do thyroid hormones do
they regulate growth, development and metabolic rate
why are females more susceptible to thyroid disease
the immune system attacks the thyroid
more mistakes like this occur in females because of response in pregnancy
why does TSH increase in primary hypothyroidism
the production in the anterior pituitary gland is not inhibited by T3 or T4
what is T4 also known as
thyroxin
describe Grave’s disease
whole gland is smoothly enlarged and overactive
need to remove the thyroid gland
autoimmune
Ab bind to and stimulate TSH receptor in thyroid
cause goitre and hyperthyroidism
Ab bind to muscles behind the eyes - exophthalmos
Ab stimulate the growth of shins and cause pretibial myxoedoma (hypertrophy)
what is pretibial myxoedema
the swelling (non-pitting) that occurs on the shin's of patients with Grave's disease growth of soft tissue
