Gas chromatography-mass spectrometry measurement of 6beta-OH-cortisol/cortisol ratio in human urine: a specific marker of enzymatic induction.
Clin Chem Lab Med
; 39(12): 1234-9, 2001 Dec.
Article
em En
| MEDLINE
| ID: mdl-11798083
ABSTRACT
The urinary 6beta-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 chromatography-mass spectrometry with isotope dilution (GC-ID-MS) method for the simultaneous determination of urinary free cortisol (UFC) and 6beta-OH-cortisol (6beta-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 101) and for 6beta-OH-cortisol 123 pg injected (signal-to-noise ratio 101). The intra-assay and the inter-assay imprecision were 4.69% and 7.4% for 6beta-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 6beta-OHC/UFC compared to controls (p<0.0001), whereas adults undergoing methadone therapy and patients with acute alcohol intoxication exhibited a significantly lower urinary 6beta-OHC/UFC ratio (p<0.05 and p<0.01, respectively). The proposed method allows a rapid and accurate assessment of the 6beta-OHC/UFC ratio.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Hidrocortisona
/
Hidrocarboneto de Aril Hidroxilases
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Adult
/
Humans
Idioma:
En
Ano de publicação:
2001
Tipo de documento:
Article