1b Hypopituitarism & Anterior Pituitary dysfunction Flashcards
what are the anterior pituitary hormones
Growth Hormone Prolactin Thyroid stimulating hormone Lutenising hormone/Follicle stimulating hormone Adrenocorticotrophic hormone
What does FSH and LH do in men?
FSH: spermatogenesis
LH: testosterone production
where does the pituitary sit
sella turcica of sphenoid bone
what does the anterior pituitary rely on?
the hypothalamus (to regulate function by releasing or inhibiting factors)
what factors are released by the hypothalamus for the AP
growth hormone releasing hormone somatostatin thyrotrophin releasing hormone dopamine gonadotrophin releasing hormone corticotrophin releasing hormone
what is a primary endocrine disease
disease where the pathology originates in the gland itself e.g ovaries
what is a secondary endocrine disease
disease where the pathology originates in the signals from the hypothalamus/anterior pituitary
what is primary hypothyroidism
thyroid doesn’t produce thyroxine
Hashimotos - autoimmune
T3&4 fall TSH high
what is secondary hypothyroidism
thyroid functioning, no releasing signals
TSH falls, T3/4 fall
Why can’t we measure TSH or CRH
located only in hypothalamic pituitary portal system
what is primary hypoadrenalism
Addisons disease
adrenal cortex damaged/destroyed by autoimmune eg TB
ACTH high, cortisol low
How do we measure fT4?
Measure for 6 days
what is secondary hypoadrenalism
adrenal cortex functioning,
but can’t make ACTH
ACTH falls, cortisol low
When do we take cortisol measurements?
suspected hypo: 9am cortisol (when it should be at its highest)
suspected hyper: midnight cortisol (when it should be at its lowest)
what is primary hypogonadism
gonads not functional
LH and FSH high, test/oest low
Another test to measure ACTH and GH
Insulin tolerance test, give them hypoglycaemia to see if release of these hormones (GH and ACTH) are normal and then measure Cortisol to see if its primary or secondary.
what is secondary hypogonadism
gonadotrophs (pituitary) damaged/hypothalamus damage
LH/FSH fall, test/oest fall
congenital causes of hypopituitarism
mutations for anterior pituitary transcription e.g PROP1
pattern of cortisol hormones
diurnal
what are the signs of congenital hypopituitarism
deficient in GH (main one) & at least one more hormone since birth
hypoplastic (underdeveloped) anterior pituitary
acquired causes of hypopituitarism
Tumours
infection eg meningitis
traumatic brain injury
pituitary surgery
pituitary apoplexy/ haemorrhage
peri-partum infarction (sheehan’s syndrome)
what is hypophysitis
inflammation of the pituitary or infundibulum
What does hypopituitarism usually describe?
Anterior pituitary dysfunction
what is pituitary apoplexy
bleeding into a pituitary adenoma (causing sudden enlargement and damaging the pituitary)
What is panhypopituitarism?
Total loss of anterior and posterior pituitary function
what is the name for complete loss of pituitary function (post. and ant.)
panhypopituitarism
what are the causes of pituitary apoplexy
haemorrhage
less commonly infarction
what procedures may cause radiotherapy-induced hypopituitarism
acromegaly treatment (radio right to pit.) nasopharyngeal carcinoma treatment (indirect)
what hormones are most sensitive to radioactivity
Growth hormone and gonadotrophins and prolactin
Prolactin
how long does the risk of radiotherapy persist for?
up to 10yrs
requires annual assessment
How does radiotherapy cause hypopituitarism?
destroys DNA so cell eventually die - brain cell have slow turnover so can take years
how does hypopituitarism affecting LH/FSH present?
reduced libido
secondary amenorrhoea
erectile dysfunction
reduced pubic hair
how does hypopituitarism affecting ACTH present?
fatigue
no salt balance issues
how does hypopituitarism affecting TSH present?
fatigue, weight gain
how does hypopituitarism affecting GH present?
reduced quality of life, short stature in children
how does hypopituitarism affecting Prolactin present?
inability to breastfeed
what is sheehan’s syndrome?
post-partum hypopituitarism secondary to hypotension/post-partum haemorrhage
how does sheehans syndrome happen?
pituitary swells so anterior pituitary is more likely to be damaged following hypotension during delivery, causing pituitary infarction
what are the signs of sheehans syndrome
lethargy, anorexia, weight loss, failure of lactation!!, failure to resume menses!!!
!!- most obv
what happens to the pituitary during pregnancy
enlargement **(lactotroph hyperplasia)
why is only the anterior pit affected in sheehans
diff portal system
what is the onset of pituitary apoplexy?
dramatic and sudden
often precipitated by anti-coagulants
what are the signs of pituitary apoplexy
severe sudden onset headache
visual field defect - bitemporal hemianopia
possible diplopia and ptosis (droopy eyelids)
how does apoplexy show up on MRIs and what is it treated by?
- anticoags
- white ball
what methods can be used to diagnose hypopituitarism
blood tests, dynamic pituitary function tests (stress test), pituitary MRI
what hormone dysfunction cannot be treated
prolactin
what is the guidance for treating hypopituitarism affecting GH?
daily injection of GH
measure response by improvement in quality of life and plasma IGF-1
how to confirm GH treatment is working
assess quality of life and measure response to this
measure plasma IGF-1
what is the guidance for treating hypopituitarism affecting TSH
once daily levothyroxine
aim for fT4 above middle of reference range
what is the guidance for treating hypopituitarism affecting ACTH?
prednisolone once daily AM
or
hydrocortisone 3x daily
what is an adrenal crisis
dizziness, hypotension, vomiting, weakness triggered by intercurrent illness
can collapse and die
what should patients taking replacement steroids be advised to do?
keep steroid alert pendant
double steroid dose if fever/intercurrent illness
if unable to take tablets, inject IM or come to A&E
what are the guidelines for hypopituitarism affecting LH/FSH in men?
replace testosterone topically or IM
if fertility required - gonadotrophin injections, sperm production should resume 6-12 months after
when is fertility in men best conserved?
if secondary hypogonadism developed after puberty (gonads are right size/development)
what are the guidelines for hypopituitarism affecting LH/FSH in women?
oral or topical oestrogen
addition of progesterone if uterus is intact to prevent endometrial hyperplasia
if fertility is required, carefully timed IVF and gonadotrophin injections can induce ovulation
signs/presentation of pituitary apoplexy
sudden onset - blood/haemorrhage in cavernous sinus
cranial III defect as blood compresses this - ptosis
radilogical diagonsis of hypopit?
empty sella
apoplexy
adenoma
