Pituitary gland and Disorders Flashcards
\ant pituitary blood supply?
no arterial blood supply but receives blood through a portal venous circulation from the hypothalamus
pituitary thyroid axis
hypothalamus releases TRH , causes pituitary to release TSH, causes thryoid to release T3 +T4 -ve feedback loop
if you remove thyroid what would happen to TSH Levels ?
increase
what happens to levels of FSH and LH during menopause
increase due to a lack of negative feedback mechanism
HPA AXIS?
hypothalamus releases crth , pituitary releases ACTH
negative feedback cause adrenals to release cortisol
what hormones does the hypothalamus control
GHRH sms
GnRH
CRH
TRH
Dopamine
what hormones do the pituitary control
GH
LH FSH
ACTH
TSH
Prolactin
common examples of pituitary diseases ?
Benign pituitary adenoma
* Craniopharygioma
* Trauma
* Apoplexy / Sheehans
* Sarcoid / TB
Tumours cause ?
1- Pressure on local structure ie optic nerves would show bitemporal hemianopia
2 -Pressure on normal pituitary- hypopituitarism
3-Functioning tumour- is it producing hormones
why does pituitary tumoir cause bi temporal hemianopia
, pressure on the optic chiasm , visual field defects
how to differentiate snot and CSF
CSF- has glucose
what colour would a patient not be able to see if they had a visual defect
RED
hypopituitary in men would present as …?
PALE
no body hair
central obesity
functioning pituitary tumours?
prolactinoma
acromegaly and gigantism
cushings disease
why would gigantism occur
pituitary tumour is pressing on the pituitary gland causing hypopituitary
do not go through puberty
WHAT is a prolactin
a hormone made by lactotrophs by the ant pit
causes breasts to grow and make milk during pregnancy and after birth
presentation of prolactinoma in men
low testosterone
erectile dysfunctioj
reduced facial hair
low libido
presentation of prolactinoma in females
amenorrhoea
oligomenorrohoea
infertility
galactorrhoea
low libido
INVESTIGATIONS for prolactinoma
1st line- serum prolactin if elevated
2nd line- pituitary MRI
TREATMENT for prolactinoma
1st- dopamine agonist ORAL cabergoline
2nd line - HRT
what is thelarche
start of puberty caused by oestrogen
what occurs during thelarche
ductal proliferation
site specific adipose deposition
enlargement of the areola and nipple
incidence of precocious puberty
90% patients female
IF BOY- REFER IMMEDIATELY MIGHT BE BRAIN TUMOUR
treatment for precocious puberty
GnRH super agonist to supress pulsatility of GnRH secretion
what is acromegaly
endo disorder resulting from excessive growth hormone
physical signs of acromegaly
bitemporal hemianopia
acral enlargement
big lips
rigid eyebrows
tall
wide nasal bone
large hands
profuse sweating
pathophysiology of acromegaly
-GHRH released from hypothalamus and stimulates the release of GH from the ant pit
-excess gh from ant pitresults in excessive production of IGF-1 which is responsible for inappropiate growth
what can cause acromegaly
pituitary tumor that releases GH -
causes THE RELEASE OF IGF1 in liver
what inhibits the release of GH
SOMATOSTATIN
high levels of glucose
DOPAMINE
epidemiology of acromegaly
3.3 per million
mean age of diagnosis is 44
mean duration of symptoms is 8yrs
acromegaly comorbidities
arthiritis
HT
sleep apnea
headache
stroke
insulin resistant
diabetes
investigations for acromegaly
1st line- insulin like growth factor 1 test
gold standard- oral glucose tolerance test
treatment for acromegaly
1st line - transsphenoidal resection surgery
2nd line - somatastatin analogie
3rd line- GH receptor
4th line- dopamine agonist
define prolactinoms
benign adenoma ( lactotroph tumor) of pituitary gland producing excess prolactin
causes of prolactinoma
unknown, some genetic association
signs and symptoms of prolactinoma
visual field defect
headache
menstrual integrity
infertility
galactorrhoea
most common pituitary mass
non functioning pituitary adenomas
what is rathkes cyst
Single layer of epithelial cells with mucoid,
cellular, or serous components in cyst fluid
what is meningioma a complication of
radiotherapy
what do meningiomas usually present with
loss of visual acuity
endocrine dysfunction
HPA AXIS
Hypothalamus releases ctrh
pituitary releases acth
adrenal glands release cortisol
describe the cortisol circadian rhythm
low in the evenings
peak in the middle of night
begins to dip as you wake up
declines throughout the day until you sleep
what controls the body clock
light
most common cause of primary Addison’s
autoimmune adrenalitis
60% of casesw
what is addisons disease
adrenal glands have been damaged, resulting in reduced cortisolu(ZF) and aldosterone(ZR)
secondary adrenal insifficiency is caused by ?
inadequate ACTH stimulating the adrenal glands resulting in low levels of cortisol being released
what can cause tertiary adrenal insufficiency
steroids- long period of time , stops you from producing your own sterodis
inhaler
creams
Gold standard test for adrenal insufficiency
short synacthen
performed in the morning when adrenal glands are the most fresh
give patient synthetic ACTH
blood cortisol measured at baseline , 30 , 60 mins
healthy- should produce cortisol
AI- failure of cortisol to risse
why does adrenal insuff cause weight loss
deficient in steroids - you would lose weight as you cant make your own
Physical signs of adrenal insufficiency
pigmentation and pallor
biochemistry of adrenal insufficiency
LEARN THIS
low na high k
eosinophilia
borderline elevated TSH
biochemical investigations for adrenal insufficiency
measure cortisol as soon as you wake up
renin/aldo- elevated renin in primary
synacthen test
secondary investigations for adrenal insuff
STEROIDS ?
Imaging
genetic
treatment for adrenal insuff
hydrocortisone - 2-3 times a day to replace cortisol levels 15-25mg
in primary adrenal insuff also replace aldosterone with fludrocortisone
common presentation of adrenal crisis
hypotension and cv collapsE
vomiting and diarrhoea
fever
hypoglycaemia
hyponatraemia and hyperkalaemia
management for adrenal crisis
- Take bloods if possible for cortisol and ACTH
- Immediate hydrocortisone 100mg IV, IM, (SC)
- Fluid resuscitation (1L N/Saline 1 hour)
- Hydrocortisone 50-100mg IV/IM 6 hourly
- In primary start fludrocortisone 100-200ug (when HC
<50mg)
what is Cushing’s syndrome
N
Endocrine disorder caused by the chronic abnormal elevation of cortisol (a glucocortic
Causes of cushings
Exogenous ACTH independent , oral steroid such as prednisolone
Or Adrenal adenoma
ENDOGENOUS ACTH - acth and cortisol levels high
Can be cushings disease , ant pituitary adenoma
Presentation of Cushing’s syndrome
Round moon face
Central obesity
Abdominal stria
Proximal limb wasting
Mood change
Acne
Describe the negative feedback loop for Cushing’s syndrome
Low blood cortisol stimulates the pit to produce acth
ACTH stimulates the adrenal gland to produce cortisol
Once blood cortisol levels are sufficient , negative feedback prevents excess cortisol by slowing acth production
gold standard test for cushings
dexamethosone suppression text - low dose 1mg
1st line test for cushings
raised plasma cortisol
treatment for cushings
exogenous cause - stop steroids, or reduce if used for asthma
adrenal adenoma- adrenalectomy
cushings- surgery to remove the tumor
complocations of cushings
HT
cvd
osteoporosis
DM
how does the dexamethasone test work
low dose given at night
test in the morning
if low cortisol then - normal
high /normal cortisol- cushings
what four things would you look for in someone who is suspected to have addisons
lean
tanned
tearful
tire
WHAT occurs in addisons disease
adrenal glands are damaged, resulting in reduced cortisol and aldosterone
what is SIADH
syndrome of inappropriate secretion of ADH
would you expect hypo or hypernatraemia in SIADH
Hyponataemia
as excess adh is released - increased water in the blood
plasma becomes more dilute
WHAT can cause siadh
idiopathic
post operative
infection
head injury
meningitis
pathophysiology of SIADH
- excess adh causes excess water reabsorption in the collecting ducts of kidney
-water dilutes the na and you get hyponatraemia
presentation of SIADH
headache
fatigue
confusion
muscle aches and cramps
severe hyponatraemia
treatment for SIADH
establish and treat cause of SIADH
if medication- stop it
fluid restriction
what is conns syndrome
a type of primary hyperaldosteronism caused by an adrenal adenoma
causes of conns syndrome
bilateral adrenal hyperplasia
presentation of conns
hypertension
headaches
hypokalaemia
investigation of conns
FBC
U&E
LFT
Treatment for conns
aldosterone agonists
first line investigation for primary hyperaldosteronism
aldosterone renin ratio
what is a pheocromocytoma
a tumour that secretes catechoalamines derived from chromaffin cells within the adrenal medulla
gold standard diagnosis for phaeochromocytoma
elevated plasma free metanephrine
