Pituitary gland Flashcards
location
top of the base of skull in a concavity within the sphenoid bone - pituitary fossa.
below the hypothalamus and optic chiasm
where do tumours arise
in the anterior portion
what is it split into
ant and post halves
are tumours mainly benign or malignant
benign
pituitary adenoma, pituitary neuroendocrine
what does the anterior pituitary gland do
secrete hormones
what hormones does the anterior secrete
FSH
LH
growth hormone
adrenocorticotropic
TSH
prolactin.
what does growth hormone do
somatropin
stimulates cell production and regeneration and growth
what does TSH do
hypothalamus monitors blood levels for T3/T4
regulates heart rate, respiratory rate, menstrual cycle, weight loss and gain
what does adrenocorticotropic do
triggers adrenal gland to produce cortisol
what does FSH do
testicular growth, sperm production/ ovulation
what does LH do
testosterone release, changes in ovaries to maintain cycle
what does prolactin do
helps lactation, escalated levels decrease oestrogen and testosterone levels
in males it enhances testosterone maintaining spermatogenesis
what is the presentation
low sex drive
infertility
makes prolactin
less frequent or halted periods
erection difficulty
increased milk production
what are the two types of tumour
non functioning/ non secreting [DON’T MAKE HORMONES]
functioning/secreting [DO MAKE HORMONES]
somatroph adenomas
acromegaly
growth spurts
overgrown feet + hands
corticotroph adenomas
cushings syndrome
weight gain
red and round face
high blood pressure
TSH presentation
overactive thyroid
weightloss
sweating
shaking
palpitations
what is the diagnosis process
CT/MRI
blood tests
what are the treatment options
surgery: hormones are given after
active monitoring: watch and wait, small tumours, drugs can be given to reduce hormone levels for functioning tumours
RT: recurrent or progressive non secreting tumours following surgical excision, residual disease close to optic apparatus, adverse pathological features, secreting tumours with persistent hormone elevation despite hormone blockade, not fit for surgery
what is Ki 67
proliferation of tumour cells, it is a protein which increases as the cell divides
what is the half life for cobalt 60
5.26 years
as time goes on treatments would be longer
describe the gamma knife process
holes = 5-18mm
doors lead lined
positioned in a set position
7am frame fitting
lidocaine into skin
MRI with the frame
tumour size is checked
only CTV
what must the volume of tumour be for GK
<20 cm^3
how long does GK take
15 min-4 hours
what is a risk of GK
skull fracture due to the large amounts of pressure, could cause a CSF leak
how many fractions is GK for
single
what are the risks of GK
tiredness, headaches = steroids
hypopituitarism = hormones
new cranial neuropathies: facial numbness, tingling
stroke
secondary malignancies surrounding the brain
simple analgescia
bleeding
skin lacteration
infection at insertion sites
skull fracture
what is the dose for secreting tumours to 80% IDL
21-25 Gy
> 25Gy to control acromegaly
dose limited by optic apparatus
what is the dose for non secreting tumours to 80% IDL
16Gy
what is the dose for non SRS IMRT
45-54Gy in 25-30
proton if under 25
SRS dose = size
what are the OAR
optic chiasm
lens
brain stem
normal brain
lacrimal gland
what does SRS on a linac need
a PTV, additional dose is given due to imaging
what does SRS depend on
type, size, number in brain, location
post treatment issues
hypopituitarism
hormone production deficiences
what isodose line is treatment normally prescribed to
80% at 6MV
must achieve target coverage of >99%
small fields and plans using sphere packing could be at 50%
what do low prescription lines provide
optimal sparing of normal tissue
improved conformity, hot spots increase in target which lead to radionecrosis
what isodose line can GK prescribe to
any
what hormones do posterior secrete
vasopressin/ADH: water balance
oxytocin: promotes positive feelings and child birth
[low levels of oxytocin = slow birth]
