pituitary gland physiology + diseases Flashcards
what is the pituitary gland split into
anterior and posterior
what is the anterior pituitary gland derived from
Rathke’s pouch
what does the anterior pituitary gland consist of
Island, cords of cells
Acidophils = somatotrophs and mammotrophs
Basophils
Chromophobe
what does the anterior pituitary gland secrete
TSH ACTH FSH & LH GH prolactin
what is the posterior pituitary gland derived from
extension of neural tissue
what does the posterior pituitary gland consist of
modified glial cells and axonal processes
what does the posterior pituitary gland secrete
ADH
oxytocin
what diseases affect the posterior pituitary gland
diabetes insipidus
SIADH
what diseases affect the anterior pituitary gland
hyper and hypo function
what is SIADH
inappropriate ADH secretion
what causes SIADH
ectopic secretion of ADH by tumours
what causes diabetes insipidus (DI)
DIDMOAD ADH deficiency/renal resistance to ADH surgery tumours inflammatory disorders of pituitary and hypothalamus
what is the diagnostic test for diabetes insipidus
water deprivation test
what is the normal result in a water deprivation test
urine/serum ratio >2
what result in a water deprivation test would suggest diabetes insipidus
<2
when would you suspect cranial diabetes insipidus
if urine/serum ratio improves after DDVAP (Desmopressin acetate tablets) is given
what is the treatment of diabetes insipidus
desmospray
desmopressin tablets
desmopressin injection
when would a desmopressin injection be given
in an emergency
post pituitary surgery
what is cranipharyngioma
tumour derived of remnants of Rathke’s pouch.
where does cranipharyngioma usually arise
within the sella
at what age does cranipharyngioma usually affect patients
5-15
60-70
what are the symptoms of cranipharyngioma
headaches
visual disturbances
growth retardation (if a child)
what is the treatment of cranipharyngioma
radiation
what is the side effect of treatment of cranipharyngioma
SSC may develop but this is rare
what are the causes of pituitary hypofunction
surgery/radiation sudden haemorrhage ischaemic necrosis tumours inflammatory conditions
what disease is caused by a decrease in TSH
hypothyroidism
what disease is caused by a decrease in LH or FSH
hypogonadism
what disease is caused by a decrease in ACTH
hypoadrenal
what are the symptoms of pituitary hypofunction in FEMALES
menstrual irregularites infertility abdominal obesity loss of axillary and pubic hair dry skin and hair growth retardation (if a child)
what are the symptoms of pituitary hypofunction in MALES
impotence gynaecomastia loss of facial, axillary and pubic hair dry skin and hair growth retardation (if a child)
what is the treatment of pituitary hypofunction
hormone replacement
what would be included in hormone replacement
thyroxine hydrocortisone desmospray/tablets HG injections (SC) sex steriods
what must be done when starting a male on testosterone
monitor prostate via PR exam and PSA
monitor FBC for polycythaemia
what side effect may occur with oral testosterone tablets, how is this checked
hepatitis
monitor LTFs
what are the options for testosterone treatments
IM injection every 3-4 weeks (sustanon)
Skin gel (testogel, tostran)
Prolonged IM injection 10-14 wks (nebido)
Oral tablets (restandol)
what causes acromegaly
excess GH
what are the symptoms of acromegaly
giantism (if happens before fusion of epiphyseal) thickened soft tissues = nose, jaw, hands snoring/sleep apnoea High BP HF Diabetes Headaches Colonic polyps and colon cancer
what investigations can be done foracromegaly
IGF1 levels
GTT (suppression test)
what is the diagnostic investigation for acromegaly
GTT suppression test
what is the normal values you expect from a GTT investigation
HG is suppressed to <0.4
what values would you expect from a GTT investigation of acromegaly was present
GH is unchanged after glucose (>1), may even rise
what is the treatment of acromegaly
pituitary surgery
how can you check if the surgery for acromegaly has been successful
retest GGT
retest IGF1
when would you repeat surgery
if GTT >1 after 1st surgery
what drugs can be used to treat acromegaly
somatostatin analogues
dopamine agonists
GH antagonists
give examples of somatostatin analogues
Sandostain LAR
lanereotide
octreotide
give an example of a dopamine agonist, when do they work best
cabergoline
works best if there is co-secretion of prolactin
give an example of a GH antagonist, when are they used
pegvisomant
LAST LINE
how do GH antagonists work
binds to G receptor to block GH activity
how do GH antagonists affect GH and IGF1 levels
IGF1 decreases
serum GH may increase
what is themes common type of pituitary adenoma
prolactinoma
what is a prolactinoma
tumour which produced prolactin
what causes raised prolactin levels
pregnancy & breastfeeding prolactinoma stress drugs hypothyroidism
what dugs causes raised prolactin levels
dopamine antagonists e.g. metoclopramide
antipsychotics
what are the symptoms of prolactinoma in MALES, when do they present
late presentation Impotency Visual field abnormalities Headache Anterior pituitary malfunction
what are the symptoms of prolactinoma in FEMALES, when do they present
Early presentation Galactorrhoea (30-80%) Menstrual irregularity Amenorrhoea Infertility
what are the investigations of prolactinoma
serum prolactin
MRI of pituitary
visual field testing
pituitary functin tests
what serum prolactin levels would make you suspect prolactinoma
> 1000 on 2 or more occasions
what is the treatment of prolactinoma
dopamine agonists
give examples of dopamine agonists
cabergoline = most common
quinagolide
bromocriptine
what are the two types of pituitary adenomas
microadenomas <1cm
macroadenomas >1cm
what are pituitary adenomas derived from
cells of the anterior pituitary
how are pituitary adenomas classified
by the type of hormone produced
what is a pituitary adenomas that does not produce hormones called
non-functioning
what do the symptoms of pituitary adenomas depend on
which hormones are produced by the pituitary adenomas
what symptoms would you suspect in a pituitary adenoma producing prolactin
infetility
lack of libido
amenorrhea
what symptoms would you suspect in a pituitary adenoma producing GH
increase in IGF1
gigantism or acromegaly
what symptoms would you suspect in a pituitary adenoma producing ACTH
cushings
