Carbohydrate-deficient transferrin (CDT), new marker of chronic alcoholic abuse and its determination by capillary zone electrophoresis

Introduction: Alcoholism represents one of the most important medical and social problems in the western world with important consequences for the individual and the society. For objective diagnosis of alcohol abuses several markers have been proposed, among which carbohydrate deficient transferrin, known as CDT, because of its high diagnostic sensitivity and specificity has become the most used marker in both clinical and forensic environments. Currently the determination of CDT is performed using commercial kit based on extraction of CDT isoforms onto anion exchange disposable cartridges followed by a immunoassay of the eluates. In addition instrumental methods are available including isoelectric focusing, anion exchange liquid chromatography, mass spectrometry and recently capillary electrophoresis. The aim of the present work was to present a brief review of the analytical methods for CDT determination and to carry out a comparison between the results obtained with a commercial immunoassay and those obtained with a capillary electrophoretic method previously validated by our group. Methods: Serum samples from 120 subjects with different alcohol consumption have been analyzed with the immunoassay ÍT-TIA (Axis Shield) in parallel with capillary electrophoresis. The immunoassay analysis has been carried out following the producer's instructions; the capillary electrophoretic analysis has been performed using a previously validated method, based on zonal separation in borate buffer pH 8,3 with UV detection at 200 nm. Results and conclusions: Overall a highly significant (p<0,001) correlation between immunoassay and capillary electrophoresis has been found (R=0,8721). On the contrary the correlation was not significant (R=0,2567) at values close to immunoassay cut-off. This evidence affects the reliability of immunoassay results particularly at the concentration values most interesting for forensic analysis, i.e. close to the cut-off between normal and pathological values. In conclusion, an instrumental confirmation of CDT results from the immunoassay is needed, at least for the samples "positive" at the screening analysis.