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Adrenal Labs
Endocrine
Question | Answer |
---|---|
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 |