Affiliation:
1. Obesity Research Center Research Institute for Endocrine Sciences Shahid Beheshti University of Medical Sciences Tehran Iran
2. Centre for Endocrinology Barts and the London School of Medicine, QMUL London UK
3. ENETS Centre of Excellence Royal Free Hospital London UK
4. Green Templeton College University of Oxford Oxford UK
Abstract
AbstractCushing's syndrome (CS) is a rare disorder, once exogenous causes have been excluded. However, when diagnosed, the majority of cases are adrenocorticotropic hormone (ACTH)‐dependent, of which a substantial minority are due to a source outside of the pituitary, ectopic ACTH syndrome (EAS). Differentiating among pituitary‐dependent CS, Cushing's disease (CD) and an ectopic source can be problematic. Because non‐invasive tests in the evaluation of CS patients often lack adequate sensitivity and specificity, bilateral inferior petrosal sinus sampling (BIPSS), a minimally invasive procedure performed during the investigation of ACTH‐dependent CS, can be extremely helpful. BIPSS is considered to be the gold standard for differentiating CD from the EAS. Furthermore, although such differentiation may indeed be challenging, BIPSS is itself a complex investigation, especially in recent times due to the widespread withdrawal of corticotrophin‐releasing hormone and its replacement by desmopressin. We review current published data on this investigation and, in the light of this and our own experience, discuss its appropriate use in diagnostic algorithms.