title: Performance of the 4-mg intravenous dexamethasone suppression test in differentiating Cushing disease from pseudo-Cushing syndrome.
abstract: BACKGROUND
  Discriminating Cushing disease (CD) from pseudo-Cushing syndrome (PCS) is a challenging task that may be overcome with the 4-mg intravenous (IV) dexamethasone suppression test (DST).
  
  
  OBJECTIVE
  Assess the performance of the 4-mg IV DST in the differential diagnosis between CD and PCS in well-characterized patients.
  
  
  METHODS
  Retrospective comparative study of subjects seen in a tertiary care unit (November 2008 to July 2011).
  
  
  METHODS
  Thirty-six patients with PCS and 32 patients with CD underwent 4-mg IV dexamethasone infusions from 11 am to 3 pm. Areas Under ROC Curves (AUCs) were estimated and compared for ACTH and cortisol measured at 4 pm the same day (day 1) and 8 am the next day (day 2). The ROC curve of the marker with the highest AUC was used to determine the threshold with the highest specificity for 100% sensitivity.
  
  
  RESULTS
  The AUC of ACTH at 8 am on day 2 was estimated at 98.4% (95% CI: [92.1-100]), which is significantly greater than that of ACTH at 4 pm on day 1 (P=0.04) and that of cortisol at 8 am on day 2 (P=0.05). For ACTH at 8 am on day 2, the threshold with the highest specificity for 100% sensitivity was estimated at 14.8 ng/L. At this threshold, the sensitivity was estimated at 100% [89-100] and the specificity at 83.3% [67-94].
  
  
  CONCLUSIONS
  The 4-mg IV DST is an easy and accurate tool in distinguishing CD from PCS. It deserves thus a better place in establishing the diagnosis of CD.
authors.affiliation: Fédération d'endocrinologie, groupement hospitalier Est, Hospices Civils de Lyon, 69500 Bron, France.
authors.forename: Migueline
authors.initials: M
authors.lastname: Nouvel
authors.affiliation: Service de biostatistique, Hospices Civils de Lyon, 69003 Lyon, France; Université de Lyon, 69000 Lyon, France; Université Lyon 1, 69100 Villeurbanne, France; CNRS, UMR5558, laboratoire de biométrie et biologie évolutive, équipe biotatistique-santé, 69100 Villeurbanne, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Rabilloud
authors.affiliation: Laboratoire d'hormonologie, groupement hospitalier Est, Hospices Civils de Lyon, 69008 Lyon, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Raverot
authors.affiliation: Service de biostatistique, Hospices Civils de Lyon, 69003 Lyon, France; Université de Lyon, 69000 Lyon, France; Université Lyon 1, 69100 Villeurbanne, France; CNRS, UMR5558, laboratoire de biométrie et biologie évolutive, équipe biotatistique-santé, 69100 Villeurbanne, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Subtil
authors.affiliation: Service d'endocrinologie, groupement hospitalier Sud, Hospices Civils de Lyon, 69310 Pierre-Bénite, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Vouillarmet
authors.affiliation: Service d'endocrinologie, groupement hospitalier Sud, Hospices Civils de Lyon, 69310 Pierre-Bénite, France.
authors.forename: Charles
authors.initials: C
authors.lastname: Thivolet
authors.affiliation: Service de neurochirurgie, groupement hospitalier Est, Hospices Civils de Lyon, 69008 Lyon, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Jouanneau
authors.affiliation: Fédération d'endocrinologie, groupement hospitalier Est, Hospices Civils de Lyon, 69500 Bron, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Borson-Chazot
authors.affiliation: Fédération d'endocrinologie, groupement hospitalier Est, Hospices Civils de Lyon, 69500 Bron, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Pugeat
authors.affiliation: Fédération d'endocrinologie, groupement hospitalier Est, Hospices Civils de Lyon, 69500 Bron, France; Service de biostatistique, Hospices Civils de Lyon, 69003 Lyon, France; Université de Lyon, 69000 Lyon, France; Inserm, U1028, 69008 Lyon, France. Electronic address: gerald.raverot@chu-lyon.fr.
authors.forename: Gérald
authors.initials: G
authors.lastname: Raverot
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D019540:Area Under Curve; D003480:Cushing Syndrome / Q000175:diagnosis*; D003907:Dexamethasone / Q000008:administration & dosage*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D008297:Male; D047748:Pituitary ACTH Hypersecretion / Q000175:diagnosis*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone
keywords: ACTH; Cushing disease; Dexamethasone suppression test; Dexaméthasone; Maladie de Cushing; Pituitary tumor; Pseudo-Cushing; Pseudo-Cushing syndrome; Test de freination; Tumeur hypophysaire