Design and validation of an LC-MS/MS method for simultaneous quantification of asymmetric dimethylguanidino valeric acid, asymmetric dimethylarginine and symmetric dimethylarginine in human plasma.

Asymmetric dimethylguanidino valeric acid (ADGV), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are three arginine metabolites which have utility in the assessment of cardiovascular disease, renal disease and non-alcoholic fatty liver disease (NAFLD). Translation of these research metabolomic markers into routine clinical use requires the development of robust assays with appropriately assessed preanalytical variables and traceable clinical reference intervals. A hydrophilic interaction liquid chromatography (HILIC) tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of ADGV, ADMA and SDMA was developed. Sample stability and collection conditions were scrutinised to determine any preanalytical factors that could affect quantification under routine laboratory conditions. Patient samples from 120 males and 120 females were used to derive preliminary reference intervals. All three analytes were quantifiable in human plasma using unique MS/MS transitions. The analytes were stable for up to a week once separated from red cells, though reduced stability was observed upon extraction of the analytes from plasma. The assay was linear for concentration of ADGV between 1.6 nmol/L and 200 nmol/L and for ADMA and SDMA between 0.1 μmol/L and 4.0 μmol/L. The accuracy for all analytes was 97-103% and interday and intraday imprecisions (coefficients of variation) were less than 10%. ADGV concentrations were noted to be lower in the female reference population when compared to males. The analytical method shows excellent performance and is sufficiently robust to be used in the clinical investigation of cardiovascular disease and NAFLD.