Inferior Petrosal Sinus Sampling
Cushing syndrome results from excess production of the hormone cortisol. The release of cortisol is controlled by adrenocorticotropic hormone (ACTH), which can be produced in several locations throughout the body. One location is the pituitary gland, which is located in a region behind the eyes and inside the skull. An evaluation for a patient with Cushing syndrome may include inferior petrosal sinus sampling (IPSS). In this procedure, two microcatheters are navigated under x-ray guidance to venous sinuses in the region of the skull base deep behind the nose, the location where the pituitary gland drains. A medication (corticorelin) is then administered and serial blood samples are obtained and tested for levels of hormone to determine the location of abnormal ACTH release.