Diurnal variation of 6beta-hydroxycortisol in cardiac patients

• Published in: Physiological research Vol. 56; no. 3; pp. 307 - 313
• Main Authors: Micuda, S, Sispera, L, Hodac, M, Parízek, P, Fuksa, L, Brcáková, E, Cerman, J, Cermanová, J, Martínková, J
• Format: Journal Article
• Language: English
• Published: Czech Republic 2007
• Subjects: Adult; Aged; Chromatography, High Pressure Liquid; Cytochrome P-450 CYP3A - metabolism; Heart Diseases - urine; Humans; Hydrocortisone - analogs & derivatives; Hydrocortisone - urine; Male; Middle Aged; Sensitivity and Specificity
• ISSN: 0862-8408

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.