Adrenal gland disorders Flashcards
(34 cards)
which hormones are produced by the adrenal cortex
Mineralocorticoids: (aldosterone)
glucocorticoids: cortisol
androgens (testosterone)
which hormones are produced by the adrenal medula
epinephrine and norepinephrine (activated by ACh through the muscarinic receptor)
what’s the function of mineralocorticoids
most important is aldosterone which causes Na/water reabsorption
and K/H excretion
other mineralocorticoids are corticosterone and 11deoxycorticosterone
name the androgens and their function
Testosterone, DHEA(dehydroepiandrosterone), androstenedione
help with sexual development
whats the function of ACTH
stimulates androgen and cortisol release
where are the receptors for cortisol (plasma membrane or intracellular)
since they are lipid soluble (steroids), they diffuse though the membrane and bind to intracellular receptors
which hormones control cortisol secretion
pituitary-adrenal axis
hypothalamus (paraventricular nucleus) releases CRH=> induces the release of ACTH=> induces cortisol release (though cAMP/PKA)
ACTH activates desmolase which converts cholesterol into pregnenolone=> the rest of the steps
when is physiologic cortisol secretion at its highest levels
6AM, its released cyclically (as a rhythm)
Is cortisol transported freely in plasma ?
its poorly soluble so its bound to Cortisol binding globulin (CBG) 90%
CBG levels increases with increase estrogen (same as TBG)
what are the functions of cortisol
increases sensitivity of blood vessels to nor/epinephrine = hypertension
sequesters lymphocytes to the, inhibit NF-KB, spleen/nodes, block neutrophil migration, blocks histamine release from mast cells = immunosuppression
increase gluconeogenesis, less glucose uptake by fat and muscle, more glycogen storage but enhanced glucagon, increased lipolysis= increase serum glucose levels and increase triglycerides
blunted epidermal cell division= skin striae (stretch marks), thing skin, easy bruising
inhibits osteoblasts= osteoporosis, osteopenia
what are the layers of adrenal cortex and what’s their function
GFR =>ACE
Glomerulosa =>aldosterone
Fasciculata =>cortisol/corticosterone/cortisone
Reticularis =>epinephrine/norepinephrine
what are the causes of Cushing’s syndrome
ACTH independent :
adrenal adenomas, glucocorticoid therapy
ACTH dependent:
ectopic secretion
Cushing’s disease (pituitary ACTH secreting tumor)
what’s the cause of hyperpigmentation in ACTH dependent Cushing’s syndrome
ACTH and MSH (melanocyte stimulating hormone) share the same precursor which is proopiomelanocortin, when you need more ACTH then MSH will also be synthesized which will cause hyperpigmentation
how do you test for Cushing’s syndrome
since cortisol secretion is rhythmic, we have to do either:
- 24h urine free cortisol
- saliva test, measured at night
- low dose dexamethasone suppression test
(normally low dose dexamethasone will depress ACTH, so you take it at night and in the morning you measure it and ACTH will be decreased, if we have cushings syndrome, this low does has no effect and no inhibition of ACTH will be seen)
high dose vs low dose Dexamethasone suppression test
low dose is used to detect if we have cushing’s syndrome or not, if we have suppressed ACTH then there is no cushings syndrome (this does not tell us the cause of cushings syndrome if it exists )
adenomas on the other hand will RESPOND to high dose dexamethasone, while ACTH secreting tumors (ectopic ACTH secretions) will not. so this will give us the cause of the cushings syndrome
how do you treat cushings syndrome
surgery
ketoconazole:(antifungal) inhibits desmolase which converts cholesterol into pregnenolone. this leads to lower cortisol synth. this also lowers androgen synthesis which causes gynecomastia
what are the types of adrenal insufficiency
PRIMARY: adrenal insufficiency, low Cortisol and aldosterone but high ACTH
SECONDARY: low ACTH and low cortisol but aldosterone is normal
adrenal insufficiency symptoms
Loss of cortisol: weight loss abdominal pain postural hypotension weakness hypoglycemia
Loss of aldosterone:
potassium retention => hyperkalemia
Na loss =>hypovolemia
H retention => acidosis
skin hyperpigmentation in primary adrenal insufficiency
when there is primary adrenal insufficiency, ACTH will raise to compensate.
ACTH and MSH have the same precursor, so when ACTH increase, MSH will increase too and cause hyperpigmentation
whats adrenal crisis
acute adrenal insufficiency
manifestation is SHOCK, hypoglycemia, nausea and vomiting, fatigue
definition of Addison’s disease, which parts of the adrenal gland is affected and what are its causes
definition: primary adrenal insufficiency
autoimmune adrenalitis: antibody and cell mediated disorder caused by antibodies to 21-hydroxylase, this will result in atrophy of adrenal gland and loss of cortex ONLY, medulla is spared
infections: fungal, CMV, tuberculosis
whats waterhouse-friderichsen syndrome
acute adrenal insufficiency caused by a hemorrhage into the adrenals. it is associated with meningococcemia
e.g. patient with meningitis with acute onset of shock
what are common causes of secondary adrenal insufficiency
glucocorticoid therapy: exogenous steroids causes adrenal to hypo function which will on the long term causes atrophy
P.S no skin findings since ACTH isn’t elevated
and no hyperkalemia since aldosterone is not affected
primary aldosteronism, definition, causes, diagnosis and treatment
high aldosterone which causes
hypertension (high water and NA)
hypokalemia (loss of K)
alkalosis (loss of H)
common causes bilateral idiopathic hyperaldosteronism
diagnosis:
high plasma aldosterone
low renin activity since hypervolemia is caused by aldosteronism, renin-angiotensin will undercompensate
if we have high renin activity and high plasma aldosteron => renal artery stenosis, CHF, low volume
treat with spironolactone. aldosterone antagonist
