Abstract
The ratio of the hydrophilic metabolite 6 beta-hydroxycortisol to its parent compound cortisol has recently been demonstrated to be a specific marker for human CYP3A oxygenase activity. We have developed a sensitive and simple single-run high-performance liquid chromatographic method for the quantification of urinary free cortisol and 6 beta-hydroxycortisol using dexamethasone as internal standard. The urine samples (1 ml) are applied to Sep-Pak cartridges, which are washed with water and eluted with ethyl acetate-diethyl ether (4:1, v/v). The organic extracts are washed sequentially with alkaline and acidic solutions saturated with sodium sulfate and subsequently concentrated to dryness. After reconstitution in ethanolic water, the samples are analyzed on a reversed-phase gradient system using ultraviolet absorbance detection at 254 nm. The within- and between-day coefficients of variation (C.V.) for the assay where both in the range of 5-10%. The reference interval for the 6 beta-hydroxycortisol/cortisol ratio of eleven healthy non-smoking subjects was 2.77-26.88 with an average of 10.09 +/- 6.89 (S.D.). The method constitutes an improvement over previous methods and is suitable for routine assessment of the 6 beta-hydroxycortisol/cortisol ratio requiring only 1 ml of urine or less.
Originalsprog | Engelsk |
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Tidsskrift | Journal of chromatography. B, Biomedical applications |
Vol/bind | 660 |
Udgave nummer | 1 |
Sider (fra-til) | 23-9 |
Antal sider | 7 |
ISSN | 1572-6495 |
DOI | |
Status | Udgivet - 3 okt. 1994 |