Development and Validation of Liquid Chromatography/Stable Isotope-Dilution Tandem Mass Spectrometry Method for Measurement of Dexamethasone, Total Cortisol and Free Cortisol in Human Plasma

Background Cortisol plays a role in the regulation of metabolic homeostasis. Dexamethasone is powerful synthetic glucocorticoid that acts as an anti-inflammatory and immunosuppressive agent. Plasma free cortisol, which has low concentration blood, cortisol fraction provides biological activity. It emphasized measurement dexamethasone, total levels can directly affect results dexamethasone suppression test, routinely used to exclude endogenous hypercortisolemia patients with adrenal adenoma, important differential diagnosis.
 Purpose In this study, precise rapid method was developed for plasma samples, besides demonstrating clinical applicability samples from adenoma patients. 
 Methods Method optimization studies were performed using liquid chromatography-tandem mass spectrometry stable isotope dilution-multiple reaction monitoring. Results The assay demonstrated good linear dynamic range 0.5–20 μg/L, 5–200 μg/L 0.5–100 respectively. values intra- inter-day precisions analytes ≤6.9% accuracies ranging 91.6% 113.0%.
 Conclusion Measurement these parameters be reliably diagnose diseases causing hypercortisolemia.