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USMLE2 Medicine 03

Endocrine - Adrenal

QuestionAnswer
Cushing Syndrome prolonged exposure to high levels of cortisol/steroids
Cushing syndrome affects K levels how? hypoK because of the mineralocorticoid effect of steroids (increases absorption of salt and water)
what is best test if you think your pt has Cushing's dexamethasone suppression. give dexamethasone at night (dex=cortisol) --> normal should suppress ACTH --> normal cortisol level by the morning. A positive test is a high cortisol level in the morning - (dex wasn't able to suppress ACTH).
how would pt on phenytoin, carbamazepine, or rifampin affect the dexamethaxone suppression test? increases the metabolism of dex --> won't suppress ACTH effectively --> high (abnl) cortisol levels in the AM
how would pt under stress (starvation, anorexia, bulimia, EtOH withdrawal, depression) affect the dexamethaxone suppression test? stress increases glucocorticoid levels --> high cortisol in the AM (abnl)
How to diagnose Cushing's dexamethaxone suppression, then confirm with 24h urine cortisol (will be high in Cushings)
high dose dexamethasone test will tell you what? distinguish between pituitary ACTH or ectopic. pituitary ACTH will be suppressed with high-dose dex (source of cortisol is adrenal --> ACTH can still be suppressed by dex via pituitary response to feedback inhibition); ectopic will not be suppressed.
if can't resect an adrenal tumor, what is the treatment? ketoconazole or metyrapone (blocks production of cortisol)
function of aldosterone reabsorb Na (reabsorbing water with Na) and excreting K and H.
what is the diff between primary and 2 hyperaldosteronism? primary = stimulus for overproduction is in the adrenal (i.e. unilateral/BL adrenal adenoma). 2= stimulus is extra-adrenal (excessive licorice ingestion).
high salt diet (normally shuts off aldosterone) --> high urine aldosterone and low plasma renin primary hyperaldosterone. need to confirm result with CT of adrenals
how to treat adrenal adenoma surgical resection
how to tx BL adrenal hyperplasia spironolactone (blocks aldosterone)
Bartter Syndrome secondary hyperaldosterone (no HTN, no edema). defect in loop of Henle --> defect in Na K 2Cl transporter --> causes NaCl loss --> dec intravascular volume
juxtaflomerular hyperplasia --> increased renin; nl to low BP; no edema; hypo K; met alkalosis; defect in renal conservation of NaCl high renin, high aldosterone --> secondary hyperaldosterone (Bartter's Syndrome)
Addison's disease hypo-cortisol/hypo-adrenal
pt with weakness, intolerance to stress, personality changes (irritability, restlessness), small heart, hypoTN, wt loss, sparse axillary hair, hyperpigmentation of the skin (diffuse bronzing of exposed and unexposed body parts) Addison's (hypo cortisol/hypo-adrenal)
fever, hypotension, low Na, high K mild acidosis Acute Addisonian crisis
How to dx Addison's disease Screen: administer ACTH and measure cortisol before and after (will be low after - won't respond to ACTH stimulation).
Labs in pt with Addison's - WBC's, Na, K, H, glucose, cortisol, urine 17 hydroxycorticosteroid Labs will show eosinophilia; low aldosterone effects: low Na, high K, mild acidosis. Hypoglycemia, low cortisol, low 17-OH-corticosteroid.
how to manage Addison's disease replace glucocorticoids, mineralocorticoids, NaCl, pt education
how to tx adrenal crisis 1. get cortisol level, 2. IVF, 3. hydrocortisone
who is at risk for adrenal crisis? 1. pt with adrenal insuff under major stress (infection/surgery/life change), 2. BL adrenal infarction/hemorrhage, 3. pt abruptly withdrawn from chronic glucocorticoid therapy.
What is pheochromocytoma? B9 tumor from chromaffin cells (neuroendocrine cells found in the medulla of the adrenal gland, part of SANS, derived from embryonic neural crest) that secrete catecholamines (NE, epi, dopamine - familial n no HTN)
diseases with pheochromocytoma The vonMEN's get pheo's: MEN II/III, vonRechlinghausen (NF1), von Hippel Lindau retinal cerebellar hemangioblastomatosis.
solitary pheo lesions on which side of body? R adrenal
pheo secretions 1. dopamine - familial, no HTN, 2. epi - tachy, sweating, flushing, HTN, 3. NE if extra-adrenal pheo (celiac, SMA or IMA ganglia)
HA, profuse sweating, palpitations, tremor, apprehension, CP, n/v, temporary HTN with tachy pheo-related catecholamine crisis
how to dx pheochromocytoma best screen: 24 h urine collection showing free catecholamines, VMA, metanephrines
when testing for metanephrines, what must you warn the pt of? can't smoke 4 h before test because smoking can inc plasma-free metanephrines
If plasma metanephrines and urine catecholamines are equivocal, what test next for pheochromocytoma Clonidine --| epi. Normally, you would get decreased epinephrine levels. If high, then pheo.
How to determine tumor size in pheo? Chromogranin levels correlate with tumor size; CT; MRI
If can't find a pheo on CT, what to use? MIBG
DDx of pheo essential HTN, anxiety, factitious, intracranial lesion, autonomic epilepsy
how to manage pheo? control BP with alpha blockers (phentolamine/phenoxybenxzamine) - do not use other anti-HTN meds before successful BP control with these meds! THEN surg resection (curative)
primary vs secondary hypogonadism primary is increased LH/FSH, but testes/ovaries do not respond with production of androgens. secondary is low LH/FSH that causes decreased gonadal hormone production.
causes of primary hypogonadism high LH/FSH, but testes/ovaries dysfxn. 1. Kleinfelter, 2. anorchia, 3. castration, 4. radiotherapy, 5. infxn (mumps, TB, leprosy), 6. chemo
causes of secondary hypogonadism 1. hypopit, 2. hypothalamic lesions, 3. Kallman syndrome (hypo hypo, decreased smell)
pre-pubertal hypogonadism (underdeveloped external genitals, high-pitched voice, no beard) deficiency of LH/FSH (secondary hypogonad) - hypopit
Adult pt with youthful appearance, obese, long extremities, small Adam's apple, gynocomastia, retarded bone age, urine 17-keto-steroid is low, testosterone low hypogonadism
how to tx hypogonadism testosterone
male breast CA Kleinfelter's
Kleinfelter's chromosomes 47XXY
pt with gynecomastia, elevated LH/FSH, sterility, no libido, small testes, MR, urine 17ketosteroid low, serum testosterone low, serum estradiol elevated Kleinfelter's
Created by: christinapham