adrenal axis Flashcards
what is adrenal axis and what does it contain
bodys stress control system , it contains 3 parts hypothalamus , pituitary gland, adrenal glands
what is conns syndrome
primary hyperaldosteronism - overproduction of aldosterone from adrenal cortex caused by adrenal adenoma
excess mineralcorticosteroids increase activity of Na/K what is the result
sodium retention causes ECf volume expansion and HTN
Potassium loss results in hypokalemia
what are key features of conns syndrome
low K
high BP
what type of ABG is common in conns syndrome
metabolic alkalosis - excess aldosterone increase secretion of H ions into lumen of medullary collecting tubules
what should be discontinued before investigations of conn syndrome
BB
ACEI
ARB
spironalactone
what is the best initial screening test for conns
plasma aldosterone: renin ratio (ARB)
investigations of conns syndrome
-plasma renin= would be low
-normal saline infusion test = normally high salt intake suppresses aldosterone in conns despite high salt no suppression
plama aldosterone: renin rattio (high)
what is primary adrenal insufficiency
addison disease (high ACTH and low cortisol)
what are causes of primary adrenal insufficiency
“ADDISON”
1) Autoimmune adrenalitis (most common cause)
2) Drugs (ketoconazole, rifampin, etomidate)
3) Destruction (infection: TB, HIV, fungal infections)
4) Infiltration (amyloidosis, hemochromatosis, metastases)
5)Surgery (bilateral adrenalectomy)
6)Other genetic disorders (congenital adrenal hyperplasia, adrenoleukodystrophy)
7) Neglect of adrenal blood supply (adrenal hemorrhage, Waterhouse-Friderichsen syndrome)
what is most common cause of secondary adrenal insufficiency
patients on long term steroid therapy
hypopituitarism
why do ppl get adrenal insuffieciency from steroid therapy
bcz when they undergo trauma they cannot release apropriate amount of cortisol bcz of suppression of CRH and ACTH by steroids
cause of tertiary adrenal insufficiency
hypothalamic disease
what are clinical features due to lack of cortisol
-hypoglycemia: cortisol gluconeogenic hormone
-hyperpigmentation: in primary adrenal insufficiency only due to high ACTH ( low cortisol stimulate ACTH and MSH secretion)
-mental symptoms
what are features due to low aldosterone
-only in primary adrenal insufficiency bcz aldosterone depends on renin- angiotensin system , not ACTH from pituitary
-hyponatremia and hypovolemia due to sodium loss -> postural hypotension
- hyperkalemia
what presents with acute adrenal crisis
hypotension
fever
confusion
coma
how to diagnose acute adrenal crisis
MUST check plasma cortisol first - draw blood then give hydrocortisone
what is the most specific test for adrenal function
standard ACTH test (cosyntropin stimulation test)
measure ACTH level before -> give iv infusion of synthetic ACTH -> measure plasma cortisol after infusion
what would happen in normal individual and not normal in cosyntropin stimulation test
*normal- rise in cortisol lvl after cosyntropin
*primary adrenal insufficiency- cortisol not inc alot even if test repeated after 5 days adrenals not respond
*secondary adrenal insufficeny- cortisol fail to respond to ACTH infusion in the start bzc not used to it but after few days will respond a little bcz adrenal glands not fully atrophied
plasma ACTH lvl
used to distinguish btwn the level of fault pituitary or gland
LOW- secondary adrenal insufficiency ( ACTH dependent cause: pituitary failure )
HIGH- with low cortisol lvl confirm primary adrenal insufficiency
cushing syndrome vs disease
cushing syndrome: broad term of excess cortisol
cushing disease: pituitary tumor producing ACTH
when are cortisol lvls the highest
morning
symptoms of high cortisol
hyperglycemia
hyperlipidemia
hypokalemia
metabolic acidosis
symptoms of low cortisol
hypoglycemia
weight loss
anorexia
nausea and vomitting
psychosis
