title: Comparison of the overnight metyrapone and glucagon stimulation tests in the assessment of secondary hypoadrenalism.
abstract: OBJECTIVE
  The insulin tolerance test (ITT) is contraindicated in a proportion of patients with suspected ACTH deficiency. The aim of this study was to investigate the diagnostic accuracy of the glucagon stress test (GST) compared with the overnight metyrapone test (OMT) in patients with contraindications to ITT.
  
  
  METHODS
  This was a prospective comparison of the GST to the OMT in patients with suspected ACTH deficiency and contraindications to the ITT. The OMT was used as the standard for comparison. The study was conducted at two tertiary referral centres for pituitary disease.
  
  
  METHODS
  Seventy-eight patients underwent contemporaneous OMT and GST of whom 61 had sufficient suppression of cortisol during the OMT to be included in the comparison. Forty had suffered traumatic brain injury, 36 had organic pituitary disorders and two were classified as 'other'.
  
  
  METHODS
  ACTH sufficiency was defined as 0800h 11-deoxycortisol ≥ 200 nmol/l on OMT and peak cortisol ≥ 440 nmol/l on GST, as per local reference ranges.
  
  
  RESULTS
  There was significant discrepancy between the proportion of patients diagnosed with ACTH deficiency using the OMT (39%) and GST (89%). From our data, a GST peak cortisol cut-off of ≥350 nm provides the combination of optimal sensitivity (71%) and specificity (57%), compared with a higher sensitivity (88%) but poor specificity (11%) using a cut-off of ≥440 nm.
  
  
  CONCLUSIONS
  The GST should be used with caution as a diagnostic test of ACTH reserve. The OMT should be used in preference to the GST to assess the hypothalamic pituitary adrenal axis where ITT is contraindicated.
authors.affiliation: Division of Diabetes, Endocrinology and Metabolism, Imperial College London, Hammersmith Hospital, London, UK.
authors.forename: Jaimini
authors.initials: J
authors.lastname: Cegla
authors.forename: Ben
authors.initials: B
authors.lastname: Jones
authors.forename: Lata
authors.initials: L
authors.lastname: Seyani
authors.forename: Deborah
authors.initials: D
authors.lastname: Papadoulou
authors.forename: Katie
authors.initials: K
authors.lastname: Wynne
authors.forename: Niamh M
authors.initials: NM
authors.lastname: Martin
authors.forename: Karim
authors.initials: K
authors.lastname: Meeran
authors.forename: Richard
authors.initials: R
authors.lastname: Chapman
authors.forename: Mandy
authors.initials: M
authors.lastname: Donaldson
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Goldstone
authors.forename: Tricia
authors.initials: T
authors.lastname: Tan
mesh_terms: D000309:Adrenal Insufficiency / Q000175:diagnosis*; D000328:Adult; D005260:Female; D005934:Glucagon / Q000494:pharmacology*; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D008297:Male; D008797:Metyrapone / Q000494:pharmacology*; D008875:Middle Aged; D010913:Pituitary-Adrenal System / Q000187:drug effects; D011446:Prospective Studies
chemical_list: D005934:Glucagon; D008797:Metyrapone