title: Bilateral inferior petrosal sinus sampling using vasopressin.
abstract: BACKGROUND
  Anatomical localization of pituitary adenoma can be challenging in adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome, and bilateral inferior petrosal sinus sampling (BIPSS) is considered gold standard in this regard. Stimulation using corticotrophin-releasing hormone (CRH) improves the sensitivity of BIPSS, however, same is not easily available in India. Therefore, we undertook this study of BIPPS using vasopressin as agent for stimulation owing to its ability to stimulate V3 receptors present on corticotrophs.
  
  
  OBJECTIVE
  To study the tumor localization and lateralization in difficult to localize cases of ACTH-dependent Cushing's syndrome by bilateral inferior petrosal sinus sampling using vasopressin for corticotroph stimulation.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Six patients (5 females) meeting inclusion criteria underwent BIPSS using vasopressin for stimulation.
  
  
  RESULTS
  All six patients had nonsuppressible overnight and low dose dexamethasone suppression test with elevated plasma ACTH levels suggestive of ACTH-dependent Cushing's syndrome. High dose dexamethasone suppression test showed suppressible cortisol in two cases, and microadenoma was seen in two patients on magnetic resonance imaging pituitary. Contrast enhanced computed tomography of the abdomen showed left adrenal hyperplasia in one case and anterior mediastinal mass with bilateral adrenal hyperplasia another. Using BIPSS four patients were classified as having Cushing's disease that was confirmed histopathologically following surgery. Of the remaining two, one had primary pigmented nodular adrenocortical disease, and another had thymic carcinoid with ectopic ACTH production as the cause of Cushing's syndrome. No serious adverse events were noted.
  
  
  CONCLUSIONS
  Vasopressin may be used instead of CRH and desmopressin for stimulation in BIPSS.
authors.affiliation: Department of Endocrinology, Army Hospital (R and R), Delhi Cantt., New Delhi, India.
authors.forename: Narendra
authors.initials: N
authors.lastname: Kotwal
authors.affiliation: Department of Endocrinology, Army Hospital (R and R), Delhi Cantt., New Delhi, India.
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Kumar
authors.affiliation: Department of Endocrinology, Army Hospital (R and R), Delhi Cantt., New Delhi, India.
authors.forename: Vimal
authors.initials: V
authors.lastname: Upreti
authors.affiliation: Department of Radiology, Army Hospital (R and R), Delhi Cantt., New Delhi, India.
authors.forename: Amandeep
authors.initials: A
authors.lastname: Singh
authors.affiliation: Commandant and Director, Military Hospital, Shillong, Meghalaya, India.
authors.forename: M K
authors.initials: MK
authors.lastname: Garg
keywords: Bilateral inferior petrosal sinus sampling; Cushing's syndrome; vasopressin