LC-MS/MS Method for the Simultaneous Determination of Free Urinary Steroids

Cortisol homeostasis is implicated in hypertension and metabolic syndrome. Two enzymes modulate cortisol availability; 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) preferentially converts inactive cortisone to cortisol, whereas 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2) converts cortisol to cortisone. In contrast, 5 alpha and 5 beta reductases inactivate cortisol by conversion to its tetrahydrometabolites: tetrahydrocortisol, allo-tetrahydrocortisol and tetrahydrocortisone. A subtle local increase in cortisol can be detected by measuring 24-h urine metabolites, LC-MS/MS being the reference method. The 11 beta-HSD2 activity is assessed based on the cortisol/cortisone ratio, and the 11 beta-HSD1 activity on the (tetrahydrocortisol + allo-tetrahydrocortisol)/tetrahydrocortisone ratio. To better understand hypertension and/or metabolic syndrome pathogenesis a method for simultaneous determination of cortisol, cortisone, tetrahydrocortisol, allo-tetrahydrocortisol and tetrahydrocortisone was developed and validated in an LC coupled with the new detector AB Sciex QTrap(A (R)) 4500 tandem mass spectrometer. The steroids were extracted from 1 mL urine, using cortisol-D4 as internal standard. The quantification range was 0.1-120 ng/mL for cortisol and cortisone, and 1-120 ng/mL for tetrahydrometabolites, with > 89 % recovery for all analytes. The coefficient of variation and accuracy was < 10 %, and 85-105 %, respectively. Our LC-MS/MS method is accurate and reproducible in accordance with Food and Drug Administration guidelines, showing good sensitivity and recovery. This method allows the assessment of 11 beta-HSD2 and 11 beta-HSD1 activities in a single analytical run providing an innovative tool to explain etiology of misclassified essential hypertension and/or metabolic syndrome.