Pituitary gland Flashcards
CRH stimulates what production
from where
ACTH
anterior pituitary
TRH form hypothalamus stimulates what production
from where
TSH
anterior pituitary
GnRH from hypothalamus stimulates what production
from where
LH and FSH
anterior pituitary
dopamine (DA) from hypothalamus stimulates what production
from where
nothing - it INHIBITS prolactin production
anterior pituitary
somatostatin from hypothalamus stimulates what production
from where
nothing - it INHIBITS GH production
anterior pituitary
what 2 things are released from the posterior pituitary
ADH/vasopressin
oxytocin
ACTH from anterior pituitary stimulates production of what
from where
cortisol
adrenal glands
TSH from anterior pituitary stimulate production of what
from where
thyroxine
thyroid gland
LH and FSH from the anterior pituitary stimulate production of what
testosterone/estradiol
when somatostatin is low = GH release from the anterior pituitary, what does this stimulation production of
from where
IFG1
liver
generally with pituitary problems, what biochemical test do you do if you suspect too much hormone
example (1)
suppression test (see if you are able to suppress the hormone from somewhere further back in the axis)
eg dexamethasone suppression test
generally with pituitary problems, what biochemical test do you do if you expect too little hormone
examples (3)
stimulation test
eg water deprivation test, insulin stress test, synacthen test
generally with pituitary problems, after youve done a biochemical test what would you do
pituitary MRI
how big is a pituitary macroadenoma
> 1cm
which structure is most commonly compressed in pituitary tumours
optic chiasm
what does optic chiasm compression present as (medical name and explanation)
bitemporal hemianopia
tunnel vision, cant see things in the peripheries
are most pituitary tumours adenomas (benign) or caricnomas (malignant)
adenomas (benign)
are pituitary adenomas common
yes
if someone presents with bitemporal hemianopia but all hormone levels are low (basically), what type of tumour do they have
why are the hormone levels low and not just normal
non functioning pituitary adenoma (doesnt produce any hormones)
pituitary is squeezed = doesnt work properly
how does a pituitary prolactinoma cause high prolactin
dopamine inhibition
apart from a prolactinoma, what else can cause hyperprolactinaemia (3)
dopamine antagonists
genetics
pituitary stalk lesion
presentation of prolactinoma in females (3)
galactorrhoea (milk secretion from breasts)
oligomenorrhoea (menstrual irregularity)
infertility
presentation of prolactinoma in males (2)
impotence
visual field defect (bitemporal hemianopia)
are women or men more likely to present with prolactinoma early
why
what symptom is indicative of this
women
more obvious/worrying symptoms
men are more likely to present with bitemporal hemianopia bc the tumour is more late stage
investigations for prolactinoma (2)
biochem - high prolactin (>3000)
pituitary MRI
prolactinoma treatment
how does this work
dopamine agonists (cabergoline)
increases dopamine = reduces tumour size (reduces prolactin secretion)
apart from GH secreting pituitary tumour, what else can cause acromegaly (increased growth hormone)
ectopic GH production from carcinoid tumour
investigations for acromegaly (to rule out ectopic GH secretion as aetiology)
pituitary MRI
increased GH causes increased … in acromegaly
IFG1 (insulin like growth factors)
presentation of acromegaly in hands (2)
wedding ring doesnt fit
spade like hands
presentation of acromegaly in feet
increased shoe size
presentation of acromegaly in everyday life
why does this happen
fatigue
protruding jaw = sleep apnoea = tired
how does acromegaly present to the GP
headaches
presentation of acromegaly in limbs (2)
proximal weakness
joint pain
presentation of acromegaly in vision
bitemporal hemianopia
presentation of acromegaly in hands
carpal tunnel syndrome
complication of acromegaly in heart
ventricular hypertrophy = heart failure
most common cause of death in acromegaly
heart failure
diagnostic test in acromegaly
explanation
oGTT (oral glucose tolerance testing)
suppression test - give glucose and measure GH 2 hours later (in normal people GH lowers, in acromegaly it stays high)
basic biochem test for acromegaly
serum IGF1
investigation to confirm pituitary tumour cause of acromegaly
pituitary MRI
investigation for visual defects in acromegaly
visual field examination
investigation for heart involvement in acromegaly (2)
ECHO
ECG
treatment of acromegaly (first line)
transsphenoidal surgery
what is increased GH called in kids
giantism
treatment options for acromegaly is surgery contraindicated/surgery done and tumour grows back (2)
radiotherapy somatostatin analogue (increases somatostatin = decreases GH secretion = decreases tumour size)
complication of acromegaly in abdomen
increased risk of colorectal cancer
disease caused by ACTH secreting pituitary tumour (other causes too)
cushings disease
see adrenal gland notes for more info
pituitary tumour in rathkes pouch (sella turcica)
craniopharyngioma
how does craniopharyngioma present on xray
calcification
treatment of craniopharyngioma
surgical excision
what is pan hypopituitarism
pituitary failure
most common cause of pan hypopituitarism
non functioning pituitary adenoma
other causes of pan hypopituitarism (apart from non functioning adenoma) (4)
sarcoidosis
pituitary stalk cut (trauma, iatrogenic in surgery etc)
drugs
pituitary artery infarction
what is pituitary artery infarction (causing bleeding) post partum (after childbirth) called
sheenans syndrome
what are hormone levels like in pan hypopituitarism
all low
presentation of pan hypopituitarism (give one for GH, TSH, FSH/LH)
short stature
obesity
menstrual irregularities/erectile dysfunction
biochem tests for pan hypopituitarism (3)
all hormone levels
synacthen test
insulin tolerance test
treatment for pan hypopituitarism (5)
think about it
hormone replacement; hydrocortisone 10-25mg/day thyroxine 100-150mcg/day GH synthetic ADH (desmospray) testosterone/oestrogen
when wouldnt you give testosterone in a male patient with pan hypopituitarism
why
if the have prostate cancer
can make it grow
is diabetes insipidus common
no
what is wolframs syndrome (DIDMOAD)
diabetes insipidus
diabetes mellitus
optic atrophy
deafness
aetiology of diabetes insipidus (4)
head trauma
pituitary haemorrhage
drugs that decrease ADH action
meningitis
cranial/neurogenic diabetes insipidus definition
ADH/vasopressin isnt produced form posterior pituitary
nephrogenic diabetes insipidus
normal ADH/vasopressin production, but doesnt work in the kidneys like it should
what happens to water in diabetes insipidus
no water reabsorption (bc no ADH) = lots of water excreted
Na conc in diabetes insipidus
high (bc water is low, so normal Na presents as hypernatraemia)
presentation of diabetes insipidus (3)
polyuria (large volumes of urine >3 llitres per hour)
excessive thirst
what does diabetes insipidus present similar to (but completely different aetiology)
diabetes mellitus
diagnostic investigation for diabetes insipidus
how does it work
water deprivation test
reduce fluid intake and patient should pee less (in diabetes insipidus they still pee lots)
treatment of diabetes insipidus (2)
synthetic ADH (desmospray or desmopressin PO/IM) fluids - to keep them hydrated bc theyre peeing so much!
complication/cause of death in diabetes insipidus
life threatening dehydration
aetiology of SIADH (2)
pituitary tumour
ectopic secretion of ASH from tumour (eg lung)
in SIADH what does increased ADH do to water
what does this do to your pee
what does this do to serum sodium levels
lots of water reabsorption
v concentrated urine
hyponatraemia - Na levels normal but lots of water = v dilute
treatment of SIADH (1)
how does it work
tolvaptan
is a vasopressin receptor antagonist = blocks ADH from binding in the kidneys = water secretion into tubules (reduced water reabsorption)
what type of drug is tolvaptan
vasopressin receptor antagonist
what does tolvaptan do to Na levels
increase them back to normal (used in SIADH where there is hyponatraemia)
