Member of the 1000 Post Club trs Posted March 21, 2008 Member of the 1000 Post Club Report Share Posted March 21, 2008 I found it interesting that this article says 40% of patients with CD will have a normal MRI. This is a long article, I just copied the last paragraph and posted it here. http://jcem.endojournals.org/cgi/content/full/87/4/1640 Optimal Response Criteria for the Human CRH Test in the Differential Diagnosis of ACTH-Dependent Cushing?s Syndrome ("By themselves, none of the noninvasive or dynamic tests used for the differential diagnosis of ACTH-dependent CS are completely reliable, and several tests may need to be used. If the hCRH test shows a rise above 20% in serum cortisol at 15 and 30 min, EC is very unlikely. However, the sensitivity of the test, in either its oCRH or hCRH form, for CD is still significantly less than 100%. What then are the recommendations for the use of the test in clinical practice? Bilateral inferior petrosal sinus sampling (BIPSS) remains the gold standard for establishing whether there is a central to peripheral gradient of plasma ACTH consistent with CD, with a sensitivity of 95?100% with a specificity of virtually 100% in major centers (1). This is, however, an invasive test requiring considerable expertise in specialist centers, and some clinicians will only option for it in cases of doubt. Forty percent of patients with CD will have a normal pituitary magnetic resonance image, whereas conversely there is a 10% prevalence of pituitary incidentalomas in the age range in which CD typically presents (1). It is, therefore, clear that magnetic resonance imaging of the pituitary cannot be relied on and weight should be given to the biochemical evaluation of a given patient. With a clear response to hCRH and an obvious pituitary lesion with stalk deviation, BIPSS may not be needed. An additional advantage of the hCRH test is that if plasma ACTH is also measured a persistently undetectable ACTH will confirm ACTH independence and the primacy of adrenal pathology (1). However, given the problems in interpreting any dynamic test in isolation, we currently consider that BIPSS or cavernous sinus sampling will continue to be necessary in the great majority of patients.") Link to comment Share on other sites More sharing options...
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