Endocrine disease Flashcards
what is endocrine system made of?
. endocrine is a signal system and is made up of discrete endocrine glands which secrete chemical messages inside of the body into the blood stream , chemical messengers go around the body to talk to other endocrine gland and induce hormonal response
. these hormones exert their effect and can regulate things like metabolism, blood sugar levels
what are the endocrine glands?
. pituitary gland -
‘ growth/lactation/thyroid’
. pineal gland - sleep wake cycle
. thyroid- metabolism
. thymus- T cell maturation
. adrenal - stress response
. pancreas - glucose metabolism
. ovaries - ovulation
. testis - spermatogenesis
what does the pineal gland do?
- pineal gland is located in the brain and it secretes melatonin that regulates circadian rhythm or sleep wake cycles
what is the most common disease that affects pineal gland?
. pineal tumours - unregulated cell proliferation within the glands which has an effect on secretion of hormones
. pineal tumours are very , very rare
. little grey area , enlarged pineal gland
<1:200,000
how common is pineal tumours within intracranial tumours?
. comprise <1% of intracranial tumours
what age is the pineal tumour peak?
. adults 35-60 years of age peak
what are the symptoms of pineal gland tumour?
. symptoms are not actually related to the hormone
. the symptoms arise due to the gland increasing in size and pushes around brain tissue around it
- headache - due to hydrocephalus - which is build up of fluid within the brain - enlargement of pineal gland can block CSF flow
- insomnia/sleep disturbances
- nausea
- blurred vision - due to increase in pressure which affects visual pathway
- upward gaze palsy ( parinaud syndrome ) - pineal gland sits near superior colliculus, which regulates up gaze movements - enlargement of pineal gland can disturb superior colliculus
- staggering gait
- hearing loss
where is pituitary gland located?
- lies close to the optic nerves
- sits below optic chaism
- sits in the hypophysial fossa of the sphenoid bone
- surrounded by sella turcica
- this means that pituitary gland is restricted in which direction it can grow when it gets a tumour because its surrounded by bones - only direction it can grow is up
what are the two regions of pituitary gland?
. anterior lobe
. posterior lobe
what does the pituitary gland link?
. pituitary gland is the main link between the nervous system and endocrine system
. lots of hormones are triggered by pituitary gland
what is the most common cause of endocrine system ?
. the most common cause of endocrine disease is tumour formation - unregulated proliferation of cells
how do pituitary tumours arise ?
- end up with more cells which are secreting more hormones - the presence of pituitary hormone hyper -secretion ( i.e. tumours )
- absence or diminution of hormone secretion caused by destruction of pituitary (i.e. caused by ischemia)
. increase in cell size causes an increase in gland size and that will have an effect on the other structures on the area , pressure is put on localised blood vessels and you can collapse down the lumen of blood vessels - this decreases blood flow
- direction and extent of local expansion and invasion of adjacent structures
non functioning adenoma (glandular tumour)- as these endocrine glands are increasing in size, the actual hormones being secreted are not changing - most dangerous - as you are getting an organ within your body increasing in size within the brain , invade adjacent structures
how common is pituitary tumour?
. represent 10-15% of intracranial neoplasms
what are different types of pituitary tumours you can have?
. when you get a pituitary tumour it can be in any one of endocrine gland cells - referred to as different tumour name
in order of prevalence
- prolactinomas - tumour of lactotroph
- growth hormone secreting adenoma - affects somatotrophs
- non secreting adenomas - most deadly - can occur in any cell type
- corticotroph adenoma (ACTH) - corticotrophs
- TSH, FSH, LH - thyrotrophs and gonadotrophs
15% of pituitary adenomas secrete >1 hormone with prolactin + growth hormone the most common combination
. tumour can affect more than one cell type
what is prolactinomas?
. prolactinomas makes up 30% of pituitary tumours
. lactotrophs become non-responsive to the prolactin inhibitory factor - loss of dopamine inhibition - over secretion of prolactin out of lactotrophs- cause secondary trauma
what are the responses around the body due to prolactinomas ?
- differs between men and women , because of the tissue types available
- women:
. amenorrhea - usually noticed - unusual lack of menstruation
. oligomenorrhea - can cause concern - irregular menstruation
. galactorrhea = witchs milk - starts production of milk ( yellow liquid ) - men:
. testicular atrophy - less testosterone being secreted
. diminished body hair
. gynecomastia = man boobs - breast tissue increase in size
. impotence
what are growth hormone secreting tumours ?
- secreted from somatotrophs
- secrets excess growth hormone
- depending on when during development you get tumour formation has different phenotype and different expression of characteristics
what happens if you get growth hormone secreting tumour during childhood?
you get gigantism - over axial elongation of the main bones in the body
e. g. in the legs and arms and fingers and toes
- growth hormone stimulates an over secretion of insulin which causes this growth
what happens if you get growth hormone secreting tumour when you’re an adult?
you get acromegaly - patients report gradual enlargement and coarsening of facial feature, hands and feet
- tumour may be large at time of diagnosis as signs and symptoms are slow
what happens when you have pituitary tumours that lead to a lack of secretion of growth hormone?
- if this occurs during puberty - pituitary dwarfism
what do corticotrophin secreting adenomas lead to ?
- you get crushing syndrome
- Females : Males (4:1)
- truncal obesity
- abdominal striae
- moon faces
- thin skin - stretch marks
- high blood pressure
- glucose intolerance
- fatigue
what happens if you have FSH and LH and TSH pituitary tumour?
. least common
. usually middle aged men and women
. can go long without being diagnosed
. you get visual field loss, headache, diplopia
- in men - decrease libido/energy
- TSH rare <1% of pituitary adenomas
what are non secreting adenomas ?
- 3rd most common pituitary tumour
- as they are non-secreting you don’t see a phenotype - they secrete hormones at right level
- only know about tumour due to the large tissue size
- tumour without endocrine symptoms are large at time of diagnosis
- you get severe frontal headache ( 50% of patients )
- as the pituitary gland increases in size it can only grow upwards - pressure is put on optic chaism axons - this leads to visual field defects
- this results in visual field defect ( monocular )
- also known as bi-temporal hemianopia
- more likely to lose superior temporal view than inferior
what happens at the optic chaism when the pituitary gland increases in size?
- temporal retina not crossing at the optic chaism
- nasal retina crosses midline at optic chaism
- when pituitary tumour grows , it will put pressure on the crossing axons
- nasal retina is responsible for temporal view
- loss of temporal visual field