adrenal gland Flashcards
what us aldosterone regulated by?
renin-angiotensin system and plasma potassium
what is the pathway to cortisol production?
hypothalamus–>ant. pituitary–>adrenal cortex
CRH ACTH
–> cortisol
what are the 6 classes of steroid receptors?
Glucocorticoid
Mineralocorticoid
Progestin
Oestrogen
Androgen
Vitamin D
what type of hormone is cortisol?
corticosteroid
what are the CNS effects of cortisol?
mood lability
euphoria/psychosis
lowers libido
what are the bone & connective tissue effects of cortisol?
accelerates osteoporosis
lowers Serum calcium
lowers collagen formation
lowers wound healing
what are the immunological effects of cortisol?
lowers:
capillary dilatation/permeability
leucocyte migration
macrophage activity
inflammatory cytokine production
what are the metabolic effects of cortisol?
carbohydrate: increases blood sugar
increases lipolysis, central redistribution
increases proteolysis
what are the circulatory/renal effects of cortisol?
increased cardiac output
increased bp
increased renal blood flow and GFR
what are the most common causes of primary adrenocortical insufficiency?
addison’s
congenital adrenal hyperplasia (CAH)
adrenal TB/malignancy
what are the clinical features of addison’s disease?
anorexia, weight loss
fatigue
dizziness and low bp
abdominal pain, nausea and vomiting
skin pigmentation
what causes addison’s disease?
autoimmune destruction of the adrenal cortex
how do you diagnose adrenal insufficiency?
suspicious biochemistry- hyponatraemia and hyperkalaemia
short synacthen test- measure plasma cortisol before vs after iv or im ACTH injection
cortisol >500 after ACTH can pretty much rule out adrenal insufficiency
adrenal insufficiency also usually have high ACTH, high renin and low aldosterone
what is the treatment for adrenal insufficiency?
hydrocortisone as cortisol replacement
fludrocortisone as aldosterone replacement
education- need more steroids if ill, cant stop suddenly
what is the treatment for adrenal crisis?
fluids- normal saline
iv / im hydrocortisone
treat the underlying cause
what is the treatment for secondary adrenal insufficiency?
hydrocortisone (aldosterone production intact so don’t need fludrocortisone)
what is the diagnostic test of cushing’s syndrome?
low dose dexamethasone suppression test
what is the most common cause of cortisol excess?
iatrogenic cushing’s syndrome sure to prolonged high dose steroid use
what do you suspect if there is hypertension + hypokalaemia?
primary aldosteronism
what is the definition of primary aldosteronism?
autonomous production of aldosterone independent of its regulators (angiotensin II + potassium)
what are the CV actions of aldosterone?
increase BP
LVH
atheroma
what is the most common cause of primary aldosteronism?
bilateral adrenal hyperplasia
how do you diagnose primary aldosteronism?
- confirm aldosterone excess
measure plasma aldosterone and renin and express as ratio
if ratio raised do saline suppression test
failure of aldosterone to suppress by >50% with 2 litres confirms PA - confirm subtypes with CT and/or vein sampling
what is the management of primary aldosteronism?
surgery- unilateral laprascopic adrenalectomy in adrenal adenoma
if bilateral use MR antagonists e.g. spironolactone
