pituitary physiology and pathology Flashcards
what is the anterior pituitary also called and where does it derive from
Adenohypophysis - rathke’s pouch
what is the posterior pituitary also called and where does it derive from
neurohypophysis - extension of neural crest
what hormones does the ant pituitary secrete
ACTH, GNRH, TSH, prolactin, GH, FSH, LH, MSH
what hormones does the post pituitary secrete
ADH and oxytocin
what is the water deprivation test
stop water for several hours and test urine osmolarity (will not have changed) then give desmopressin (ADH) and allow normal drinking
what water deprivation results would indicate a pituitary problem and a kidney problem
pituitary: urine concentrates after ADH.
Kidney: urine still not concentrated
in the insulin stress test or glucagon test, what should hypoglycaemia cause a rise in
GH, ACTH and cortisol
in the synthACTHen/ dexamthasone test what should happen to plasma cortisol after the injection
it should rise (if it does not adrenal problem, usually used for addisons)
what size is a macroadenoma vs a microadenoma of the pituitary
macro = >1cm, micro <1cm
what can macroadenomas compress if they are too big
compress optic chiasm, compress CNVIII, IV, V, VI
what visual loss is associated with optic chiasm compression
bitemporal hemianopia
what conditions can non-functioning pituitary adenomas cause from reduced hormone secretion
hypoadrenalism, hypothyroidism, hypogonadism, GH deficiency, (diabetes insipidus)
how do you treat non-functioning pituitary adenomas
transsphenoidal surgery - replace hormones
what effect does prolactin have on the body
breast milk production and breast growth
what effect does prolactin have on GnRH
suppresses release of GnRH causing infertility and reduced libido
what physiological causes increase prolactin
breast feeding and pregnancy (also stress and rise in sleep)
what drugs can cause raised prolactin
dopamine antagonists eg metoclopramide (dopamine inhibits prolactin release)
what is the most common functional pit tumour
prolactinoma
what are symptoms of prolactinoma in females
early presentation, galactorrhoea, period irregularities, amenorrhoea, infertility, low libido
what are symptoms of prolactinoma in males
late presentation, impotence, visual field disruption, impotence
what investigations are done for prolactinoma
serum prolactin (high), MRI, visual field, pit function tests (decreased)
how do you treat prolactinoma
dopamine agonists eg carbergoline
what are side effects of dopamine agonists
N+V, low mood
when would you surgically remove a prolactinoma
macroadenoma, failed drug
what are symptoms of acromegaly (adenoma)
giantism, thickened soft tissue (jaw, skin, large hands, sweaty), snoring + sleep apnoea, hypertension, headaches, T2DM
how do you diagnose acromegaly
serum GH, glucose tolerance test (giving glucose should suppress GH but will not affect acromegaly)
what is first line treatment for acromegaly
surgery - radio less effective on its own
what somatostatin analogues is used in acromegaly, what effect does it have, how do you give it, what are side effects
OCREATIDE: reduces GH and shrinks tumour/ sub cut injection monthly/ GI upset and GALLSTONES
what dopamine agonist is used in acromegaly and is it effective
cabergoline - not V effective
what GH antagonist analogues is used in acromegaly, what effect does it have, how do you give it
PEGVISOMAT: good response but does not give tumour, sub cut daily injections, last line as expensive
what can cause pan hypopituitarism (10(
pit tumours, local brain tumours, iatrogenic, granulamtous (TB, sarcoidosis), vascular, trauma, mets, hypothalamic disease, autoimmune (Sheenan), infection (meningitis)
what are symptoms of pan hypopituitarism
a lack of pit hormones: menstrual irregularities, impotence, obesity, loss of facial, axillary and pubic hair, dry skin, growth retardation (growth failure, hypothyroid, hypogonadism, hypoadrenalism, diabetes insipidus)
how can you test for hypopituitarism
FPTs, hormone blood tests (testosterone, GH etc), synACTHen test and insulin tolerance
what hormones are given when treating pan hypopituitarism
HRT: thyroxine, hydrocortisone, ADH, GH, sex steroids
what is a benefit of giving GH in hypopituitarism and how do you give it
improves wellbeing, cardiac function, muscle mass, bone density, decreases cholesterol - SC daily injection
what is a risk of giving testosterone in hypopituitarism and how do you give it
prostate enlargement, polycythaemia, hepatitis - give monthly IM injection
what can cause diabetes insipidus
tumour, trauma, idiopathic
what is diabetes insipidus and what are symptoms of it
ADH deficiency - polyuria, thirst, urine osmolarity similar to plasma osmolarity (not concentrates)
how would you diagnose diabetes insipidus
water deprivation test
how do you treat diabetes insipidus
desmopressin (ADH)
