Investigation of endogenous corticosteroids profiles in human urine based on liquid chromatography tandem mass spectrometry.

The accurate and precise measurement of endogenous corticosteroids in urine is a powerful tool to understand the biochemical state in several diseases. In this study, a rapid, accurate, and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of 67 endogenous gluco- and mineralo-corticosteroids and progestins has been developed and validated. Sample preparation, chromatographic separation, and mass spectrometric detection were optimized. Urine samples (0.5 mL) were hydrolyzed with β-glucuronidase and the released analytes were extracted by liquid-liquid extraction. The chromatographic separation was performed in 20 min after redisolution of the extract. MS behavior of endogenous corticosteroids was evaluated in order to select the most specific precursor ion ([M+H](+), [M+NH4](+), or [M+H-nH2O](+)) for the detection. MS/MS determination was performed under selected reaction monitoring mode using electrospray ionization in positive mode. The method was shown to be linear (r>0.99) in the range of endogenous concentrations for all studied metabolites. Limits of detection (LOD) below 1 ng mL(-1) were typically obtained for analytes with a 3-oxo-4-ene structure whereas LODs below 15 ng mL(-1) were common for the rest of analytes. Recoveries were higher than 80% and intra-assay precisions below 20%, evaluated at three concentration levels, were found for most steroids. No significant or moderate matrix effect, ranging from 54 to 155%, was observed for most of the analytes. The applicability of the method was confirmed by analyzing 24h urine samples collected from twenty healthy volunteers and comparing the results with previously established normal ranges. The wide coverage of corticosteroid metabolism, together with short analysis time, low sample volume, simple sample preparation, and satisfactory quantitative results make this method useful for clinical purposes.