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USMLE2 Medicine 03
Endocrine - Adrenal
| Question | Answer |
|---|---|
| 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
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