Simultaneous measurements of cortisol and cortisone in urine and hair for the assessment of 11β-hydroxysteroid dehydrogenase activity among methadone maintenance treatment patients with LC-ESI-MS/MS.

Abstract

The activity of 11β-hydroxysteroid dehydrogenases (11β-HSD) is traditionally assessed using the ratio of cortisol to cortisone in urine or saliva. However, these biomarkers only reflect the local activity of 11β-HSD, and are easily affected by circadian variation of cortisol secretion. The shortcomings might be overcome by hair analysis. The present study aimed to develop an enhanced assay for simultaneous measurements of cortisol and cortisone in both hair and urine samples. The samples were collected from 29 patients under methadone maintenance treatment. The cortisol and cortisone were extracted either by solid phase extraction from a 20-mg milled hair sample after a 14-h incubation in 1ml of methanol, or by twice liquid-liquid extraction from a 20-fold diluted urine sample. The analyses were performed using high performance liquid chromatography tandem mass spectrometry with electrospray ionization in negative mode. Limits of detection and quantification were 0.5 and 1.25pg/mg for hair steroids and 0.2 and 0.5ng/ml for urinary steroids, respectively. The recoveries were more than 97%. The intra- and inter-day coefficients of variation were less than 10%. The ratios of cortisol to cortisone in hair and urine were both less than one, but did not correlate with each other. A possible reason for the lack of correlation was that the ratios in hair and urine might mostly reflect the activity of 11β-HSD type 2 in the eccrine sweat gland and in the kidney, respectively. Additionally, a significant correlation was observed between results obtained using external standard quantification and internal standard quantification.