addisons + cushings Flashcards
addisons
when the adrenal glands have been damaged, resulting in;
- reduced cortisol
- reduced aldosterone
commonest cause of adrenal insufficiency in UK
autoimmune destruction (80%)
(addisons / primary adrenal insufficinecy)
secondary adrenal insuffieciency
due to inadequate ACTH + lack of stimulation of the adrenal glands, leading to low cortisol
-> loss of damage to pituitary gland
causes of secondary adrenal insufficiency
tumours - pituitary adenomas
surgery to pituitary
radiotherapy
trauma
sheehans syndrome - where major post partum haemorrhage causes AVN of ptuitary
tertiary adrenal insufficiency
inadequate CRH release by hypothalmus
- usually result of long term steroids, when stopped suddenly, pituitary doesnt wake up
(why steroids need to be tapered off)
addisons presentation
- lethargy, weakness, anorexia, N+V, weight loss
- salt craving, thirst
- hyperpigmentation (primary only) excess ACTH (neg feedback)
- vitiligo, loss of pubic hair
- hypotension (postural), hypoglycaemia
what electrolyte changes are seen in addisons
hypOnatraemia
hypERkalaemia
hypoglycaemia
raised creatinine + urea due to dehydration
addisons investigations
ACTH stimulation test (short synacthen test)
CT / MRI of adrenals - primary
MRI of pituitary - secondary
antibodies in autoimmune adrenal insufficiency
21-hydroxylase antibodies
adrenal cortex antibodies
(addisons)
management of addisons
- hydrocortisone (+injection dose to tx adrenal crisis)
- fludrocortisone
(both gluco- + mineralcorticoid replacement)
education
- importance to not miss glucocorticoid
- sick day rules
management of addisons with intercurrent illness
glucocorticoid (hydrocortisone) should be doubled, with fludrocortisone staying the same
causes of addisonian crisis
- sepsis or surgery (acute exacerbation of insufficiency
- adrenal haemorrhage - waterhouse-friderischsen
- steroid withdrawal
management of addisonian crisis
hydrocortisone 100mg IM/IV
1L saline over 30-60 mins - with dextrose if hypoglycaemia
(no fludrocortisone required)
cushings syndrome
features of prolonged high levels of glucocorticoids in bodys
glucocorticoids = cortisol
mineralcorticoids = aldosterone
cushings DISEASE
a pituitary adenoma secreting excessive ACTH, stimulates excessive cortisol from adrenals. ->adrenal hyperplasia
(a cause of cushings SYNDROME)
causes of cushings syndrome
ACTH dependent
- cushings disease
- ectopic ACTH - small cell lung cancer
ACTH independent;
- steroids
- adrenal adenoma/carcinoma
pseudo-Cushings
- alcohol excess/severe depression
–> insulin stress test to differentiate
electrolyte disturbance seen in cushings syndrome
a hypokalaemic metabolic alkalosis
- impaired glucose tolerance
cushings investigations
- overnight (low-dose) dexamethasone suppresion test (morning cortisol not suppressed)
–> a high dose dexamethasone supression test is then used to localise the underlying pathology
(CRH stimulation - if pituitary source then rises, ectopic/adrenal wont)
how would cushing disease present after a high dose dexamethasone suppression test
cortisol - suppressed
ACTH - suppressed
(pituitary adenoma -> ACTH secretion)
how would cushing syndrome caused by an adrenal adenoma present after a high dose dexamethasone suppression tes
cortisol - NOT suppressed
ACTH - suppressed
how would ectopic ACTH syndrome present after a high dose dexamethasone suppression tes
cortisol - not suppressed
ACTH - not suppressed
e.g -> small cell lung cancer
cushings presentation
- round, moon face
- central obesity
- abdominal striae
- hirsutism
- easy bruising poor skin healing
what can a patient presenting with cushings + hyperpigmentation tell you
excess ACTH either from -
- cushing disease
- ectopic ACTH
(absent in adrenal adenoma or exogenous steroids)
