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Adrenal Labs

Endocrine

QuestionAnswer
Adrenal insuff dx: labs AM cortisol (low); ACTH stim (low); plasma ACTH (>100: primary AI) (nml: 5-45 R/O primary AI; find cause of secondary/tert AI)
Cushing syn: ACTH-indept: Adrenal lesion/tumor: next step is adrenal CT; exogenous source; Plasma ACTH level is low (< 5 pg/mL)
Cushing syn: ACTH-dependent: Plasma ACTH level is normal or high (>15 pg/mL); Either ectopic production OR Pituitary adenoma = Cushing dz
Diagnosis: ACTH-dept: distinguish btw ectopic vs pituitary: CRH-Stimulation test; HD Dex suppression; Petrosal Sinus Sampling; Octreotide scintigraphy to localize ectopic source; MRI
Primary hyperaldosteronism: labs Chem7 (Hypokalemia, Metab alkalosis); Serum renin & aldosterone ( Aldo/renin ratio >20 is suspicious); 24-hr urine aldost (high in setting of low renin (<5mcg/dL) suspicious); Saline-loading; 18-OH corticosterone
Primary hyperaldosteronism: labs: 18-OH corticosterone indicative of aldosterone producing adenoma (APA)
Primary hyperaldosteronism: imaging Abd CT (esp of adrenals); Adrenal vein sampling: for localization (cath of left an&d right adrenal veins & the IVC, looking for lateralization of elevated aldosterone level
Pheochromocytoma: Dx 24 hr urine (for Catecholamines & Metabolites: Metanephrines / VMA); Serum metanephrines/ plasma catecholamines; Imaging
Preferred test for Cushing syndrome 24 hr urine cortisol (>125 mg/dL per 24 hr)
Increased ACTH is due to: Cushing dz; Addison; ectopic ACTH-producing tumors
Decreased ACTH is due to: secondary AI: adrenal tumor; steroid medication; hypopituitarism
Acute Adrenal insuff: lab findings Low cortisol; Hyperkalemia; Hyponatremia; Elevated BUN; Hypoglycemia
Renin & aldosterone: body position levels rise following assumption of an upright position
Elevation of 17-KS indicates: tumor or hyperplasia of adrenal cortex
adrenal x-rays to: look for calcifications (poss d/t TB)
adrenal CT/MRI to: evaluate the size & shape of the adrenal glands & pituitary
17-OCHS & 17-KS useful to: detn cause of cushing syndrome
17-OCHS very high in: ectopic ACTH secretion
Hirsutism/virilization labs: Inc plasma & urine 17-KS; inc plasma ACTH
interfering substance in urine metanephrine analysis peppers
VMA: useful in dx & f/u of: pheochromocytoma; present in larger amts than other catecholamines
DHEA >1000 ng/mL will r/o: adrenal insufficiency
Cushing imaging MRI for pit tumor; CT for adrenocortical tumor
Gold standard to dx primary Addison dz Low morning cortisol <3 with high ACTH (>200 pg/mL)
Secondary adrenal insuff: Dx Low morning cortisol <5; Low ACTH in setting of low cortisol; No Response to synthetic ACTH (cortrosyn) stim test (nl >18 if adrenal is working); Insulin Tolerance Test; Metyrapone Test
ACTH & 11-deoxycortisol ACTH stims adrenal to make 11-deoxycortisol (which makes cortisol); Nml pit will drive up 11-d, if 11-d goes up & ACTH goes up, then pt has nml pit-adrenal axis;
Metyrapone Test: Give metyrapone: blocks cortisol prodn, cortisol goes down, FB to hypo-pit, if pit working, more ACTH to inc cortisol
Hypercortisolism: Dx 24 hr urine for free cortisol (if >100, prob Cushing, if >300, def Cushing; Check Cortisol at night; Suppressing Cortisol with oral dex; checking ACTH levels
Hypercortisolism: Dx: why suppress cortisol w/Dex if suppress to <5, then do not have Cushing (dex provided enough glucocorticoid to pit, signals need not prod cortisol); if ACTH >10, prob has tumor that does not respond to dex
Hypercortisolism: Dx: radiography Do not do radiographic studies prior to lab studies (poss Incidental Tumors, False Negative Scans)
ACTH measurement rarely measured directly (due to lability)
AM cortisol results: >18: r/o adrenal insuff; <3: R/I adrenal insuff; btw this range: need dynamic testing
ACTH stim test 250 mcg Cosyntropin; measure cortisol before & 30 & 60 min after injxn; pre or post >18: R/O adrenal insuff
test used to evaluate overall cortisol production 24 hr urine cortisol (AKA urine free cortisol)
preferred test for Cushing syn 24 hr urine cortisol
24 hr urine cortisol specimen 5 mL (frozen, fridge, or preservative) within 4 hr of collection
ACTH levels indicate: High: Addison; low: secondary AI
Increased ACTH d/t: Cushing dz; Addison; ectopic ACTH-producing tumors
Decreased ACTH d/t: adrenal tumor; steroid medication; hypopituitarism
Acute AI: lab findings Low cortisol; Hyperkalemia; Hyponatremia; Elevated BUN; Hypoglycemia
Cushing: lab dx 24 hr urine cort; Dex suppression test; high PM cortisol
Cushing: to detn cause of xs cortisol: Plasma ACTH level; HD Dex supp test; CRH stimulation test; Imaging (CT, MRI, US)
Secondary hyperaldosteronism More common than primary; usu d/t renal artery stenosis (curable by surg/angioplasty)
Renin & aldosterone: body position levels rise following assumption of an upright position
Elevation of 17-KS indicates: tumor or hyperplasia of adrenal cortex
adrenal x-rays to: look for calcifications (poss d/t TB)
adrenal CT/MRI to: evaluate the size & shape of the adrenal glands & pituitary
17-OCHS & 17-KS useful to: detn cause of cushing's syn
Cushing other findings Hyperglycemia; Glycosuria; Leukocytosis; Lymphocytopenia; Hypokalemia
17-OCHS very high in: ectopic ACTH secretion
Hirsutism/virilization labs: Inc plasma & urine 17-KS; inc plasma ACTH
interfering substance in urine metanephrine analysis peppers
VMA useful in dx & f/u of pheochromocytoma; present in larger amts than other catecholamines
Created by: Abarnard