title: Variability of cortisol assays can confound the diagnosis of adrenal insufficiency in the critically ill population.
abstract: OBJECTIVE
  To compare the total plasma cortisol values obtained from three widely used immunoassays and a high pressure liquid chromatography (HPLC) technique on samples obtained from patients with sepsis.
  
  
  METHODS
  Observational interventional in the general intensive care unit of a metropolitan hospital
  
  
  METHODS
  Patients admitted to the intensive care unit with a diagnosis of sepsis and fulfilling criteria of systemic inflammatory response syndrome.
  
  
  METHODS
  Standard short synacthen test performed with 250microg cosyntropin.
  
  
  RESULTS
  Two of the three immunoassays returned results significantly higher than those obtained by HPLC: Immulite by 95% (95%CI 31-188%) and TDx by 79% (21-165%). The limits of agreement for all three immunoassays with HPLC ranged from -62% to 770%. In addition, by classifying the patients into responders and non-responders to ACTH by standard criteria there was concordance in all assays in only 44% of patients.
  
  
  CONCLUSIONS
  Immunoassay estimation of total plasma cortisol in septic patients shows wide assay related variation that may have significant impact in the diagnosis of relative adrenal insufficiency.
authors.affiliation: Department of Intensive Care, Ipswich Hospital, Chelmsford Avenue, 4305 QLD, Ipswich, Australia. jeremy_cohen@health.qld.gov.au
authors.forename: Jeremy
authors.initials: J
authors.lastname: Cohen
authors.forename: Gregory
authors.initials: G
authors.lastname: Ward
authors.forename: Johannes
authors.initials: J
authors.lastname: Prins
authors.forename: Mark
authors.initials: M
authors.lastname: Jones
authors.forename: Bala
authors.initials: B
authors.lastname: Venkatesh
mesh_terms: D000304:Adrenal Cortex Function Tests; D000309:Adrenal Insufficiency / Q000175:diagnosis* / Q000209:etiology; D000328:Adult; D000704:Analysis of Variance; D002851:Chromatography, High Pressure Liquid; D003951:Diagnostic Errors / Q000517:prevention & control; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007118:Immunoassay / Q000379:methods; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D018805:Sepsis / Q000150:complications*
chemical_list: D011933:Reagent Kits, Diagnostic; D006854:Hydrocortisone