15.10 Adrenal Cortex Flashcards
adrenal cortex is composed of what three layers?
glomerulosa, fasciciulata, reticularis
glomerulosa produces
mineralcorticoids (e.g., aldo)
fasiculata produces
glucocorticoids (e.g., cortisol)
reticularis produces
sex steroids (e.g., testosterone)
What is Cushing syndrome?
Excess cortisol (hypercotisolism)
why does Cushing cause muscle weakness with thin extremities?
cortisol breaks down muscle producing amino acids for gluconeogenesis
why does cushion cause moon facies + buffalo hump + truncal obesity?
cortisol –> high glucose –> high insulin –> increased storage of fat
why does cushing cause HTN?
cortisol upregulates alpha1 recepots on arterioles
why does cushing cause osteoporosis?
inhibits osteoblasts, GI ca2+ abs, sex steroids;
increases bone resorption & urine ca2+ loss
why does cushing cause immunosuppression?
cortisol inhibits PLA2, IL2, and hist release from mast cells
why does cushing cause abdominal striae
impaired synthesis of collagen with thinning of skin
6 clinical manifestations of cushing
- muscle weakness w/ thin extremities
- moon facies, buffalo hump, truncal obesity
- abdominal striae
- HTN
- osteoporosis
- immunosuppression
how to diagnose cushing
24-hr urine cortisol levels
4 causes of cushing
- exogenous corticosteroids
- primary adrenal adenoma, hyperplasia or CA
- ACTH-secreting pituitary adenoma
- paraneoplastic ACTH secretion (small cell)
exogenous corticosteroids –>
bilateral adrenal atrophy bc steroids suppress ACTH secretion (negative feedback)
primary adrenal adenoma, hyperplasia, or carcinoma
unilateral adrenal atrophy (of the uninvolved gland)
ACTH-secreting pituitary adenoma
bilateral adrenal hyperplasia
what could you use to distinguish ACTH secreting pituitary adenoma and paraneoplastic ACTH secretion? (NB: both would result in bilateral hyperplasia)
High-dose dexamethasone
high-dose dexamethasone effect on ACTH production by a pituitary adenoma?
DECREASES it (so decreases cortisol)
high-dose dexamethasone effect on ectopic ATCH production by a small cell lung carcinoma?
NO EFFECT (so cortisol stays high)
what is conn syndrome?
hyperaldosteronism - excess aldosterone
conn syndrome presentation
HTN due to sodium retention (maybe - aldo escape with ANP?), hypokalemia, metabolic alkalosis
effect of increased aldo
increased sodium reabsorption and K+ secretion by principal cells and increased H+ secretion by alpha-intercalated cells
most common cause of primary hyperaldosteronism
sporadic adrenal hyperplasia (adrenal adenoma and carcinoma are less common)
hormone levels in primary hyperaldosteronism
high aldo low renin (high BP down regulates via negative feedback)
seen with activation of the RAS system (e.g. by renovascular hypertension or CHF)
secondary hyperaldosteronism
hormone levels in secondary hyperaldosteronism
high aldo
high renin
excess sex steroids with hyperplasia of both adrenal glands
congenital adrenal hyperplasia
most common cause of congenital adrenal hyperplasia
21-hydroxylase deficiency
21-hydroxylase is required for the production of what?
aldosterone and corticosteroids
21-hydroxylase deficiency causes steroidogensis to be shunted towards
sex steroid prodcution
cortisol levels in 21 hydroxylase deficiency
low cortisol –> increased ACTH secretion (loss of negative feedback) –> bilateral adrenal hyperplasia
electrolytes and volume status in congenital adrenal hyperplasia
hyponatremia,
hyperkalemia,
hypovolemia
lack of cortisol in 21 hydroxylase deficiency presents how?
life-threatening hypotension
congenital adrenal hyperplasia clinical presentation
clitoral enlargement in females or precocious puberty in males due to excess androgens
how would you treat congenital adrenal hyperplasia?
cortisol to suppress ACTH
lack of adrenal hormones is called
adrenal insufficiency
characterized by hemorrhagic necrosis of the adrenal glands, classically due to DIC in young children with N meningitis infection; lack of cortisol exacerbates hypotension, often leading to death
Waterhouse-Friderichsen syndrome
chronic adrenal insufficiency due to progressive destruction of the adrenal glands
Addison’s dz
causes of addison disease
- AI (west)
- TB (developed)
- lung cancer, which loves to metastasize to the adrenals
electrolyte and volume abnormalities in addison
hyponatremia, hyperkalemia
hypovolemia, hypotension
why do you seen hyperpigmentation in addison?
increased ACTH by productions stimulate melanocytic production of pigment
clinical symptoms of addison
hyponatremia + hyperkalemia
hypotension + hypovolemia
hyperpigmentation
weakness, vomiting, diarrhea
