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Flashcards in 3 - Anterior Pituitary 2 Deck (22):
1

why is dexamethasone nice for endocrinologists?

doesnt show up on cortisol assay so you can still measure pt's endogenous production of cortisol while they are on it

2

basic derangement in cushing's

glucocorticoid (cortisol) excess

3

signs/sx of cushing's

truncal obesity
moon facies
diabetes / glucose intolerance
gonadal dysfunction
hirsutism/acne (hyperandrogenism)
HTN
weakness/muscle atrophy
skin atrophy > striae, bruising
fat pads
psychiatric disturbance (hallucinations, emotional lability)
hyperpigmentation
acanthosis

4

mech for HTN in cushing's

cortisol can activate aldosterone receptor
can also have assoc hypokalemia, hypernatremia, metab alkalosis

5

mech for osteoporosis / avascular necrosis in cushing's / steroid use

inc bone resorption - pos effects on osteoclasts, dec gonadal hormones
dec bone formation - inhib osteoblasts, apoptosis, muscle weakness
dec intestinal Ca absorption
inc renal Ca excretion

6

3 problems caused by long term glucocorticoid excess

cataracts, glaucoma, gastritis/PUD

7

common sources of ectopic ACTH for ACTH dependent Cushing's

Neuroendocrine tumors - carcinoid, small cell lung CA, medullary thyroid CA, pheo, pancreatic islet tumor, gastrinoma

8

main cause of ACTH independent Cushing's

adrenal adenoma

9

order of diagnostics in Cushing's

biochemical first (find out if ACTH (in)dependent etc), then you can do imaging

10

biochemical tests to confirm Cushing's

dexamethasone suppression test
24 hr urine free cortisol
midnight serum cortisol

*random serum cortisol is not helpful!!

11

causes of pseudo-Cushing's

depression, obesity, alcohol

12

test to best distinguish cushing's from pseudo-cushing's

dexamethasone suppressed CRH stimulation test - 48 hrs of dex will suppress normally in most pseudo pts, so no stimulation w/ CRH. Cushing's pt will still respond to CRH b/c aberrant feedback inhibition

13

determining primary vs ectopic ACTH

MRI - if >5mm adenoma in pituitary, likely to be primary. if not, need to keep investigating w/

14

is this primary or ectopic ACTH Cushing's? ACTH stimulates w/ CRH and suppresses w/ high dose dex

primary

15

is this primary or ectopic ACTH Cushing's? ACTH doesn't stimulate w/ CRH and doesn't suppress w/ high dose dex

ectopic

16

inferior petrosal sinus sampling

very invasive technique to determine primary vs ectopic ACTH Cushing's
measure ratio of central ACTH to peripheral - high indicates primary
**only useful if hypercotisolism is already proven! a normal person will respond like a primary Cushing's pt on this test!

17

tx of primary ACTH Cushing's

surgical removal - transsphenoidal
drugs - ketoconazole, metyrapone, mitotane (destroys adrenal tissue - adrenocortical CA), mifipristone (RU486 - glucocorticoid receptor antagonist
radiation
adrenalectomy - risk for Nelson's dz

18

Nelson's dz

uncontrolled growth of residual ACTH producing pituitary tumor due to lack of feedback control by cortisol following adrenalectomy > extreme hyperpigmentation and muscle weakness

19

pituitary apoplexy - what is it and presentation

bleeding into pituitary > leads to hypopituitarism
30% cases - acute event w/ HA and visual disturbances, N/V
70% - silent asymptomatic

20

genetic cause of hypopituitarism

PROP-1 mutation - dont make enough pituitary neurons

21

tx of pituitary apoplexy

ICU care, IV fluids
high dose IV corticosteroids (assumed adrenal insufficiency)
craniotomy / decompression of pituitary fossa
post op evaluation for pituitary hormone deficiencies > hormone replacment

22

insulin tolerance test

gold standard for assessing pituitary hormone secretion. based on opposing roles of insulin vs cortisol and GH. cortisol and GH should increase to stabilize plasma glucose after insulin load