title: Prolactin measurement during inferior petrosal sinus sampling improves the localization of pituitary adenomas in Cushing's disease.
abstract: OBJECTIVE
  Inferior petrosal sinus sampling (IPSS) distinguishes pituitary-dependent Cushing's disease (CD) from ectopic ACTH syndrome with a high degree of certainty, but has not been reliable in predicting the location of an adenoma within the pituitary gland. We investigated whether prolactin measurements during IPSS would improve pituitary tumour localization.
  
  
  METHODS
  Fifty-four patients with suspected ACTH-dependent Cushing's syndrome who underwent IPSS between 1997 and 2009 were studied retrospectively. Twenty-eight patients who had an identifiable tumour that stained for ACTH on histopathology are the subject of this study. Intersinus ACTH gradients before and after adjustment for prolactin were compared with surgical findings and pathology.
  
  
  RESULTS
  Magnetic resonance imaging localized a pituitary adenoma in 17/28 (61%) patients. Using a maximum intersinus ACTH gradient of ≥1·4 before or after CRH stimulation, we could diagnose the tumour location correctly in 15/28 (54%) patients. By comparison, tumour lateralization by means of a dominant (≥1·4) prolactin-adjusted ACTH intersinus gradient was correct in 21/28 (75%) patients (P = 0·041). Tumour localization was correct in 23/28 (82%) patients when MRI and prolactin-adjusted ratio data were combined. Fourteen patients with proper bilateral IPS venous sampling (as determined by concurrent IPS to peripheral prolactin ratio ≥1·8) either had correct localization of the tumour (n = 12) or had a central lesion (n = 2). In none of these 14 patients was the dominant prolactin-adjusted ACTH ratio associated with a tumour on the opposite side of the gland.
  
  
  CONCLUSIONS
  Prolactin measurement, during IPSS, improves our ability to correctly localize the pituitary adenoma site in CD.
authors.affiliation: Department of Endocrinology, The Neurological Institute, The Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Guy B
authors.initials: GB
authors.lastname: Mulligan
authors.forename: Charles
authors.initials: C
authors.lastname: Faiman
authors.forename: Manjula
authors.initials: M
authors.lastname: Gupta
authors.forename: Laurence
authors.initials: L
authors.lastname: Kennedy
authors.forename: Betul
authors.initials: B
authors.lastname: Hatipoglu
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Hui
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Weil
authors.forename: Amir H
authors.initials: AH
authors.lastname: Hamrahian
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D003480:Cushing Syndrome / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D017591:Petrosal Sinus Sampling / Q000379:methods*; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology; D011388:Prolactin / Q000378:metabolism*
chemical_list: D000324:Adrenocorticotropic Hormone; D011388:Prolactin