Sebia Capillarys 2 versus the Helena Biosciences V8 capillary electrophoresis analyser for carbohydrate-deficient transferrin measurement: comparison and analytical evaluation

Evaluation of carbohydrate-deficient transferrin measurements on the V8 capillary electrophoresis system and comparison with the IFCC approved HPLC reference method and N-Latex immunonephelometric assay

OBJECTIVES

Carbohydrate-deficient transferrin (CDT) measurements are commonly used for the identification and follow-up of individuals suspected of chronic alcohol abuse. This study describes the analytical characteristics of the CDT assay on the Helena Biosciences V8 electrophoresis analyzer and compares its diagnostic performance to the International Federation of Clinical Chemistry and Laboratory Medicine approved high performance liquid chromatography (HPLC) method and the N-Latex CDT immunonephelometric assay.

METHODS

The analytical performance of the V8 assay, including the linearity and the imprecision, was studied at two separate locations. Method comparison analysis was performed by studying the correlation, bias and agreement between the V8, HPLC and the N-Latex assays in 231 patient samples.

RESULTS

The total imprecision ranged between 5.1 and 24.3% and was ≤13.1% for samples with concentrations above the clinical cut-off value (≥1.62%). The method comparisons revealed excellent correlations with r²≥0.97 for all comparisons. Measurements on the V8 showed a bias of -0.83 (-22.24%) and -0.40 (-12.26%) with the HPLC and N-Latex assays, respectively. The assays showed excellent agreements (Kappa scores ≥ 0.8) in classifying subjects with elevated CDT values. Receiver operating characteristic (ROC)-curve analysis, using the HPLC classification as reference, revealed areas under the ROC-curves of 0.981 (95% CI, 0.97-0.99) and 0.996 (0.99-1.00) for the N-Latex and V8 assays, respectively.

CONCLUSIONS

CDT measurements on the V8 assay are highly correlated with both the HPLC and the N-Latex assay and show excellent agreement in classifying subjects with elevated CDT values. Overall, the V8 CDT analysis is a robust, reliable and effective method to measure CDT concentrations in serum samples.

Monitoring of transferrin isoforms in biological samples by capillary electrophoresis

Work dealing with the monitoring of transferrin isoforms in human serum and other body fluids by capillary electrophoresis is reviewed. It comprises capillary zone electrophoresis and capillary isoelectric focusing efforts that led to the exploration and use of assays for the determination of carbohydrate-deficient transferrin as a marker for excessive alcohol intake, genetic variants of transferrin, congenital disorders of glycosylation and β-2-transferrin, which is a marker for cerebrospinal fluid leakage. This paper provides insight into the development, specifications, strengths, weaknesses, and routine use of the currently known capillary electrophoresis based assays suitable to detect transferrin isoforms in body fluids. The achievements reached so far indicate that capillary zone electrophoresis is an attractive technology to monitor the molecular forms of transferrin in biological specimens as the assays do not require an elaborate sample pretreatment and thus can be fully automated for high-throughput analyses on multicapillary instruments. Assays based on capillary isoelectric focusing are less attractive. They require immunoextraction of transferrin from the biological matrix and mobilization after focusing if instrumentation with a whole-column imaging detector is not available. Interactions of the carrier ampholytes with the iron of transferrin may prevent iron saturation and thus provide more complicated isoform patterns.

Analytical and diagnostic aspects of carbohydrate deficient transferrin (CDT): A critical review over years 2007-2017

The need for investigating alcohol abuse by means of objective tools is worldwide accepted. Among the currently available biomarkers of chronic alcohol abuse, carbohydrate-deficient transferrin (CDT) is one of the most used indicator, mainly because of its high specificity. However, some CDT analytical and interpretation aspects are still under discussion, as witnessed by numerous research papers and reviews. The present article presents a critical review of the literature on CDT appeared in the period from 2007 to 2017 (included). The article is organized in the following sections: (1) introduction, (2) pre-analytical aspects (3) analytical aspects (4) diagnostic aspects (5) concluding remarks. As many as 139 papers appeared in the international literature and retrieved by the search engines PubMed, Web of Science and Scopus are quoted.