Wednesday, May 03, 2017

NEJM review of Cushing’s syndrome

Some key points from the review follow:

Prior to the obesity epidemic assessment of the pretest probability of Cushing’s syndrome based on physical examination was relatively easy.  Nowadays it is much more difficult to clinically assess patients for Cushing's syndrome merely on the basis of the anabolic manifestations (abdominal obesity and the metabolic syndrome) due to the considerable overlap between Cushing's and the metabolic syndrome with respect to these characteristics.  However, taking into account the antianabolic effects of chronic hypercortisolism (osteoporosis, multiple bruises, thin skin) greatly enhances clinical assessment and if all three of the latter are present the pretest probability is quite high.

The optimal laboratory strategy to confirm the diagnosis is controversial.  The review author recommends a 24 hour urine free cortisol determination for laboratory confirmation followed by an ACTH level for differentiation of the type of Cushing's syndrome.  He decries the use of dexamethasone suppression testing but this view is in dispute.  Other sources (Up to Date and Harrison's) mention dexamethasone suppression testing as having a potential role in the evaluation.  Midnight sampling of plasma or salivary cortisol are also mentioned by the other sources.

Recommendations for inferior petrosal sinus sampling are variable, with the NEJM review calling for a more definitive role for such sampling.  By this point in the evaluation the hospitalist or primary physician would need some help from an endocrinologist.

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