title: Electrochemiluminescence immunoassay method underestimates cortisol suppression in ulcerative colitis patients treated with oral prednisone.
abstract: OBJECTIVE
  To evaluate cortisolemia by using conventional electrochemiluminescence immunoassay (ECLIA) method compared to liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in active ulcerative colitis (UC) patients treated with oral prednisone (PD).
  
  
  METHODS
  Twenty patients (12 males) with acute relapse of UC started oral PD at a dose of 40 mg once a day, tapered of 10 mg every 2 wk. When a stable 2-wk daily dose of 30 mg was reached, blood samples for cortisol levels' measurement were drawn in the morning in fasting conditions to determine circulating cortisol by LC-MS/MS and ECLIA assay.
  
  
  RESULTS
  Median interquartile range cortisolemia with ECLIA and LC-MS/MS method was 54.1 (185.8) nmol/L and 32.1 (124.0) nmol/L, respectively (P < 0.001). The within-patient median differences between the two methods was 23.2 (40.6) nmol/L, with higher cortisol levels for the ECLIA method. The estimated geometric mean ratio between methods was 1.85 (95%CI: 2.39-1.43) considering all data or 1.58 (95%CI: 2.30-1.09) considering only data above the limit of quantification (n = 12). The 95%CIs of the geometric mean ratio between methods confirm a statistically significant difference.
  
  
  CONCLUSIONS
  Blood cortisol levels detected with ECLIA method seems to be higher than the ones measured by LC-MS/MS, indicating a possible overestimation of them in patients treated with PD. Therefore, the cortisol suppression in patients under treatment with oral PD should not be measured using ECLIA method.
authors.affiliation: Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Manguso
authors.affiliation: Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Bennato
authors.affiliation: Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lombardi
authors.affiliation: Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy.
authors.forename: Assunta
authors.initials: A
authors.lastname: Viola
authors.affiliation: Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Riccio
authors.affiliation: Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy.
authors.forename: Livio
authors.initials: L
authors.lastname: Cipolletta
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D002853:Chromatography, Liquid; D003093:Colitis, Ulcerative / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D015536:Down-Regulation; D004334:Drug Administration Schedule; D055664:Electrochemical Techniques; D005260:Female; D005765:Gastrointestinal Agents / Q000008:administration & dosage*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007118:Immunoassay / Q000379:methods*; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011241:Prednisone / Q000008:administration & dosage*; D011446:Prospective Studies; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000893:Anti-Inflammatory Agents; D015415:Biomarkers; D005765:Gastrointestinal Agents; D011241:Prednisone; D006854:Hydrocortisone
keywords: Cortisol; Immunoassay; Liquid chromatography; Prednisone; Tandem mass spectrometry; Ulcerative colitis