title: Diurnal variation of 6beta-hydroxycortisol in cardiac patients.
abstract: The 24-hour urinary excretion of 6-beta-hydroxycortisol (6beta-OHC) and the urinary ratio of 6beta- hydroxycortisol/cortisol (6beta-OHC/UFC) have been proposed as noninvasive probes for human cytochrome P450 3A4 isoform (CYP3A4). In this study, we evaluated within- and between-day variability of 6beta-OHC excretion and 6beta-OHC/UFC ratio in nine Caucasian men with cardiac disease. Each study participant was asked to collect 24-hour urine specimens during four consecutive days in five standardized time intervals. Concentrations of UFC and 6beta-OHC were determined by immunoassay and the high-performance liquid chromatographic (HPLC) method, respectively. The HPLC method was accurate and precise, as indicated by the recovery rate of 96.5-103.3 % and less than 5.2 % and 6.3 % of the coefficient of variation for within-run and between-run assay, respectively. In patients, diurnal variations in UFC and 6beta-OHC excretion were parallel. Consequently, 6beta-OHC/UFC ratio remained stable during the day. Both, 6beta-OHC excretion and 6beta-OHC/UFC ratio showed significant relationship between 24-hour value and values measured in corresponding collection periods with best correlations obtained from night interval (22.00-06.00, r = 0.86-0.91). These results indicated that urinary 6beta-OHC excretion and 6beta-OHC/UFC ratio measured in overnight/morning urine could precisely reflect 24-hour values even in severely ill patients. In addition, a simple and sensitive HPLC method was described for determination of 6beta-OHC in urine.
authors.affiliation: Department of Pharmacology, Charles University in Prague, Faculty of Medicine in Hradec Králové, Simkova 870, Hradec Králové, Czech Republic. micuda@lfhk.cuni.cz
authors.forename: S
authors.initials: S
authors.lastname: Micuda
authors.forename: L
authors.initials: L
authors.lastname: Sispera
authors.forename: M
authors.initials: M
authors.lastname: Hodac
authors.forename: P
authors.initials: P
authors.lastname: Parízek
authors.forename: L
authors.initials: L
authors.lastname: Fuksa
authors.forename: E
authors.initials: E
authors.lastname: Brcáková
authors.forename: J
authors.initials: J
authors.lastname: Cerman
authors.forename: J
authors.initials: J
authors.lastname: Cermanová
authors.forename: J
authors.initials: J
authors.lastname: Martínková
mesh_terms: D000328:Adult; D000368:Aged; D002851:Chromatography, High Pressure Liquid; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D006331:Heart Diseases / Q000652:urine*; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000652:urine; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: C001380:6 beta-hydroxycortisol; D051544:Cytochrome P-450 CYP3A; D006854:Hydrocortisone