Adrenal insufficiency Flashcards
What is adrenal insufficiency?
Inadequate secretion of cortisol and/or aldosterone.
Why should you maintain a high index of suspicion for adrenal insufficiency?
It is potentially fatal and has a variable presentation.
Give 5 key features of adrenal insufficiency.
Fatigue, hyponatraemia, hypotension, lean, tanned, weakness, anorexia, depression, nausea and vomiting, abdominal pain
What are the 3 layers of the adrenal gland from outer to middle and what do they produce?
Zona glomerulosa - aldosterone
zona fasciculata - cortisol
zona reticulosa - sex steroids
medulla - adrenaline and noradrenaline
How is medullary release of adrenaline controlled?
By sympathetic activation
Describe the normal physiology which leads to cortisol release and inhibition.
The hypothalamus produces corticotropin-releasing factor which tells the pituitary gland to secrete adenocorticotrophic hormone. ACTH stimulates the zona fasciculata in the adrenal gland to release cortisol. This inhibits the hypothalamus and pituitary.
What causes secondary adrenal insufficiency?
Hypopituitarism
lecture
Describe the pathophysiology of primary adrenal insufficiency.
Mainly Addison’s disease, where destruction of the adrenal cortex leads to cortisol and aldosterone deficiency.
What causes tertiary adrenal insufficiency?
HPA suppression by steroids, eg inhaler, creams, etc.
What is the role of glucocorticoids?
Glucocorticoids (cortisol) are a secondary messenger from central clocks (the suprachiasmatic nuclei) to peripheral clocks (the organs) *?
(lecture 17.4.18)
What investigations would you do for adrenal insufficiency and what would they show?
- Bloods: FBC, U&E: increased K+ and Ca2+, decreased Na+ and glucose, uraemia, eosinophilia, anaemia
- 9am cortisol <100nmol/L and ACTH high in primary, low in secondary.
- Renin/aldosterone: elevated renin in primary.
- SynACTHen test: Measure cortisol, give synacthen and measure again 30 in mins.>500nmol/L = likely AI.
Why does secondary adrenal insufficiency cause increased K+ and decreased Na+?
Aldosterone causes K wasting and Na retention. There is low aldosterone so more K and less Na retained in blood.
Why does secondary adrenal insufficiency cause decreased glucose?
Cortisol inhibits peripheral use of glucose (insulin resistance) which keeps blood glucose levels up. In AI there is low cortisol so glucose is metabolised faster.
Describe the management of adrenal insufficiency.
- Hydrocortisone to obtain normal cortisol levels
2. If primary, replace aldosterone with fludrocortisone.
What is adrenal crisis?
Adrenal insufficiency resulting in hyponatraemia, hyperkalaemia, hypoglycaemia, fatigue, fever, hypotension and cardiovascular collapse. High mortality.
