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6 Cards in this Set
- Front
- Back
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What does the dexamethasone suppression test rely on?
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On the principle of negative feedback to localize the source of ACTH.
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What should normally happen when dexamethasone is given?
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It should mimic cortisol and exert negative feedback on the pituitary, decreasing ACTH output from the pituitary.
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What is the significance when a low dose dex test does not suppress ACTH?
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It indicates that Cushing's syndrome exists, but does not indicate the source of ACTH over-production.
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If the pituitary is over secreting ACTH(Cushing' disease) and you give high dose steroids, what should happen?
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The pituitary shouls respond to this negative feedback, and the ACTH level should decrease. The pituitary still responds to negative feedback, but requires a higher level than normal.
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ACTH level will be suppressed by the high dose dex suppression test. TRUE/FALSE
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TRUE.
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An ectopic site of ACTH production does not respons to negative feedback, so failure to suppress the ACTH level with high dose dex indicates an ectopic source of elevated ACTH. TRUE/FALSE
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TRUE.
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