cp2755
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A 48-year-old man comes to the physician because of the recent onset of obesity and easy bruisability. His blood pressure is 165/95 mm Hg. Dermal striae are found on physical examination. A dipstick examination of urine reveals glycosuria. Which of the following is the most appropriate next step in diagnosis?
A. Baseline plasma ACTH measurement
B. CT scans of the chest and abdomen
C. Dexamethasone suppression test
D. Measurement of midnight serum cortisol level
E. Measurement of 24-hour urine cortisol and creatinine
F. MRI scans of the head
--I am confused with the answer to this question. The answer from my book was given as C, but it seems clear to me that E is more precise. Any ideas? 
Thanks!
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| nisha
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According to kaplan, a 24 hour urine cortisol is never the best INITIAL test, always start off with a baseline (low dose) overnight dexamethasone suppression test, it is the best screening test. It is easy to do, and all pt. of Cushings have an abnormal test, but note, it is sensitive, not specific. The next test to do is the 24 hour free cortisol in urine (it is the most confirmatory diagnostic test)
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| cp2755
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Thank you. Now I understand what the first test is; however, I'm now confused about the second test.
According to the book "Nail the boards", the next step after overnight (low dose) DST is the low-dose DST (i.e. urine is collected at 24-hour intervals over 3 days for measurement of cortisol. On day 2, a low dose (0.5 mg) of dexamethasone is given by mouth every 6 hours for 48-hours.) to rule out the false positives in overnight DST.
Is 24 hour free cortisol urine collection you mentioned as the second step the same as the beginning of the low-dose DST?
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| nisha
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woah man that's complex..i am not sure i understood it...im just going according by what Charles Faselis taught at kaplan, (the red things are my arrows)
Diagnosis of CUSHINGS:
low dose dexamethasone->24 hr urine cortisol->high dose dexamethasone (if abnormal high dose dexamethasone it means a pituitary source) -> serum ACTH, high ACTH means extraneous source like unresectable lung cancer and low ACTH mean adrenal leson
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| drkpp
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short and sweet!!!!
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| dr.vasim
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Thaz gr8 Nisha.. I think u r 24/7 with kaplan. keep it up
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| nisha
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yes if match and residency don't work out...at least Kaplan will give me an interview! 
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| chemamr
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hey drkpp, I can call Sweet to Nisha, but only me. Ok?. 
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