Evidence-Based Medicine
Copyright ©2014 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 21, 2014; 20(31): 10895-10899
Published online Aug 21, 2014. doi: 10.3748/wjg.v20.i31.10895
Electrochemiluminescence immunoassay method underestimates cortisol suppression in ulcerative colitis patients treated with oral prednisone
Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Assunta Viola, Elisabetta Riccio, Livio Cipolletta
Francesco Manguso, Raffaele Bennato, Giovanni Lombardi, Elisabetta Riccio, Livio Cipolletta, Division of Gastroenterology, Cardarelli Hospital, Naples 80131, Italy
Assunta Viola, Division of Haematology and Stem Cell Transplantation Unit, Cardarelli Hospital, Naples 80131, Italy
Author contributions: Manguso F and Riccio E designed research; Manguso F, Bennato R, Lombardi G, Riccio E and Viola A performed research; Viola A stored the blood samples; Manguso F analysed data; Manguso F and Bennato R wrote the paper.
Correspondence to: Francesco Manguso, MD, PhD, Division of Gastroenterology, Cardarelli Hospital, Via A. Cardarelli 9, Naples 80131, Italy. manguso@alice.it
Telephone: +39-81-7474034 Fax: +39-81-7473018
Received: February 19, 2014
Revised: April 10, 2014
Accepted: May 25, 2014
Published online: August 21, 2014
Abstract

AIM: 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.

CONCLUSION: 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.

Keywords: Cortisol, Immunoassay, Liquid chromatography, Prednisone, Tandem mass spectrometry, Ulcerative colitis

Core tip: The determination of morning cortisol levels is used in clinical practice and as specific safety endpoint in various clinical trials. This study was designed to compare the efficacy of electrochemiluminescent assays (ECLIA) method and liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measurement of cortisolemia in active ulcerative colitis (UC) patients treated with oral prednisone (PD). Blood cortisol levels detected with ECLIA method are higher than the ones measured by LC-MS/MS, indicating a possible overestimation of them in UC patients treated with PD. Therefore, the cortisol suppression in patients under treatment with oral PD should not be measured using ECLIA method.