Clinical Chemistry and Laboratory Medicine (CCLM)
Published in Association with the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)
Editor-in-Chief: Plebani, Mario
Ed. by Gillery, Philippe / Lackner, Karl J. / Lippi, Giuseppe / Melichar, Bohuslav / Payne, Deborah A. / Schlattmann, Peter / Tate, Jillian R.
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Rank 5 out of 30 in category Medical Laboratory Technology in the 2014 Thomson Reuters Journal Citation Report/Science Edition
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Impact per Publication (IPP) 2015: 2.238
Gas Chromatography-Mass Spectrometry Measurement of 6β-OH-Cortisol/Cortisol Ratio in Human Urine: A Specific Marker of Enzymatic Induction
Citation Information: Clinical Chemistry and Laboratory Medicine. Volume 39, Issue 12, Pages 1234–1239, ISSN (Print) 1434-6621, DOI: https://doi.org/10.1515/CCLM.2001.198, June 2005
- Published Online:
The urinary 6β-OH-cortisol/cortisol ratio is a specific, non-invasive marker for evaluating inductive or inhibitory effects on cytochrome P450 3A activity. We propose a new quantitative gas chromatographymass spectrometry with isotope dilution (GC-ID-MS) method for the simultaneous determination of urinary free cortisol (UFC) and 6β-OH-cortisol (6β-OHC). The method utilizes the following: (a) addition of internal standard (2H2 cortisol) to 1 ml of urine; (b) loading on to an Extrelut column and elution with dichloromethane; (c) derivatization to dimethoxime tri-(trimethyl-silyl)-ether (MOX-TMS); (d) separation and identification by GC-ID-MS. The detection limit for cortisol was 22 pg injected (signal-to-noise ratio 10:1) and for 6β-OH-cortisol 123 pg injected (signal-to-noise ratio 10:1). The intra-assay and the inter-assay imprecision were 4.69% and 7.4% for 6β-OHC and 2.44% and 3.53% for cortisol, respectively. We used this method to analyze 57 morning urine samples of healthy volunteers and patients under different conditions. We found that chronic alcoholics had a significantly higher ratio of 6β-OHC/UFC compared to controls (p<0.0001), whereas adults undergoing methadone therapy and patients with acute alcohol intoxication exhibited a significantly lower urinary 6β-OHC/UFC ratio (p<0.05 and p<0.01, respectively). The proposed method allows a rapid and accurate assessment of the 6β-OHC/UFC ratio.
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