cherryho
Forum Guru
Topics: 30
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If Cushing is suspected, which test should be done first? 24h urine cortisol or oral dexamethasone supression?
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| drnadeemusmani
Forum Senior
Topics: 29
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24 hr urine cortisol- me thinks
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| Eagle_303
Forum Guru
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24 hr urine cortisole test = screening test
Dexamethasone suppression test = confirmatory test
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| cherryho
Forum Guru
Topics: 30
Posts: 583
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I asked this Q coz Kaplan has a flow chart showing that oral dexamethasone is the first test, but it doesn't make much sense to me.
___________________
99/99/Pass; Certified; 2003; US PhD; 2M US clerkships; GC; Chance favors only the prepared mind. - Louis Pasteur
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| nightflight1945
banned
Topics: 32
Posts: 920
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24 hour urinary cortisol level is more specific than low dose dexamethasone suppression test . Both can be the first next step in screening for urine because there is two different approaches (24 hour urinary test is recommended by myoclinic as first test), in summary I can say that you won't see both in answers in step 2 , But please be notified that Low dose Dexa test can be also positive in some other situations the most famous one is MDD so if low dose Dexa test becomes positive it should always be confirmed by 24 hour urine cortisol level .
In summary : You will find just one of them in the answers in real exam
If Low dose Dexa test is positive , always order 24 hour urinary cortisol level.
24 hour urinary cortisol level is more sepecific , but it is more difficult and inconvenient than low dose dexa ,So many use low dose Dexa as first step.
REGARDS
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| Eagle_303
Forum Guru
Topics: 77
Posts: 655
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Actually dexamethasone suppression test is of three types :
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LOW DOSE DEXAMETHASONE SUPPRESSION TEST :It is again of two types
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Over night low-dose dexamethasone suppression test = screeing test
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Standard low-dose dexamethasone suprresion test = confirmatory test
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HIGH DOSE DEXAMETHASONE TEST : for location of pathology
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| hero
Forum Guru
Topics: 42
Posts: 557
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overnight low dose dexa supression test - very sensitive but not specific - if normal - it is not Cushing. It is a screening test.
24 h urine i guess more expensive, if you can cheaper eliminate all non-diseased - that is 1st test
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