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In an outpatient clinic, a patient presents with complaints of increased weight gain. On physical exam, he has abdominal striae and increased tissue elasticity around his shoulders and upper back. You order a dexamethasone suppression test and expect that:

A. No change in cortisol on low-dose dexamethasone, but inhibition of cortisol on high dose dexamethasone; indicative of Cushing's disease

B. Inhibition of cortisol on low-dose dexamethasone, but no change of cortisol on high dose dexamethasone; indicative of Cushing's disease

C. No change in cortisol on low- dose dexamethasone, with increased cortisol on high dose dexamethasone; indicative of Cushing's disease

D. Inhibition of cortisol on low-dose dexamethasone, and no change of cortisol on high dose dexamethasone; indicative of ectopic ACTH syndrome

E. No change in cortisol on low-dose dexamethasone, but inhibition of cortisol on high dose dexamethasone; indicative of ectopic ACTH syndrome

Source : Gunner Training Programme.
 

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A. No change in cortisol on low-dose dexamethasone, but inhibition of cortisol on high dose dexamethasone; indicative of Cushing's disease
 

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Can someone further explain this, i still don't get it

Here is my understanding:
- the symptoms in the question are all indicative of Cushings syndrome. The causes of Cushings syndrome include :
1) pituitary adenoma
2) adrenal neoplasia
3) ectopic ACTH production- small cell carcinoma
4) iatrogenic- chronic steroid use

As we know, dexamethosone will cause variable effects depending on the cause, so how do we establish that the above question was talking about pituitary adenoma, why couldn't it be the other causes. Pls explain
 

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Here is my understanding:
- the symptoms in the question are all indicative of Cushings syndrome. The causes of Cushings syndrome include :
1) pituitary adenoma
2) adrenal neoplasia
3) ectopic ACTH production- small cell carcinoma
4) iatrogenic- chronic steroid use

As we know, dexamethosone will cause variable effects depending on the cause, so how do we establish that the above question was talking about pituitary adenoma, why couldn't it be the other causes. Pls explain
yes, you are saying true...but the options clearly specify as cushing disease(implies--pituitary adenoma)
cushing disease is different from cushing syndrome....cushing disease is pituitary cause of cushing syndrome
 

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Here is my understanding:
- the symptoms in the question are all indicative of Cushings syndrome. The causes of Cushings syndrome include :
1) pituitary adenoma
2) adrenal neoplasia
3) ectopic ACTH production- small cell carcinoma
4) iatrogenic- chronic steroid use

As we know, dexamethosone will cause variable effects depending on the cause, so how do we establish that the above question was talking about pituitary adenoma, why couldn't it be the other causes. Pls explain
Well, failure to suppress cortisol level with low dexamethasone suppression tests suggestive of cushing syndrom and confirm it u need to do 24 urine cortisol level, if it's high then u have confirmed cushing syndrom.
Then, high dose dexamethasone test used to identify the cause as u mentioned above.
If the cortisol is suppressed with high dose then the cause is pituitary(cushing disease), u need to do MRI.
if not suppressed wiht the high dose then it's ectopic (adrenal or lung CA), then proceed with CT & MRI for both lung and adrenals.

The pt. cortisol level is not affected by low dose test but instead is suppressed by high dose which mean it's cushing disease

So the answer would be A :)
 

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thanks

yes, you are saying true...but the options clearly specify as cushing disease(implies--pituitary adenoma)
cushing disease is different from cushing syndrome....cushing disease is pituitary cause of cushing syndrome
yes you are right, it specifies cushings disease (pituitary adenoma) so it makes sense ... thanks
 
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