Search

The measurement of CDT (Carbohydrate Deficient Transferrin) is an essential biological tool in the diagnosis and follow-up of alcohol abuse. It is also employed as a marker of abstinence for the restitution of driving licences. However, the precision of measurement, and the between laboratory homogeneity of the results are still discussed. The ion exchange followed by immunodetermination of CDT is available in two products, the Tina Quant %CDT (Roche, Mannheim, Germany) and the %CDT TIA (Bio-Rad, Hercules, United States). This multicentre study was undertaken: 1) to evaluate the analytical characteristics of these kits and the homogeneity of the results from one laboratory to another, independently of the method used, 2) to validate the differences between the proposed normal values of both kits, 3) to study the possibility of using commercial control sera as external quality control. Four analytical systems were included in the study (Roche Modular/Hitachi 717, Beckman Coulter Immage and LX20, Dade Behring BNII). Determinations were carried out on pools of sera, commercial control sera, kit controls, and 30 serums of patients. These latter were also analyzed in capillary electrophoresis in order to establish correlations between the techniques. The calibrations were stable over one 2 weeks period. The repeatability of measurements spread out from 3,1% to 24,7%, for a mean value lower than 10%. The commercial control sera provided reliable results, with values adapted to a routine quality control use. The results of the Bio-Rad applications were lower by approximately 20% than those of the Roche application, which justifies the difference of the normal values (2,6% versus 3%), and an identical classification of the patients in at least 27 of the 30 samples. We conclude that the analytical quality of the compared techniques, even if it could be improved, is sufficient to guarantee a good reliability of the results. An external quality control could be proposed by using the control sera that we tested.

Increased concentrations of high sensitivity C-reactive protein are associated with increased risk for coronary heart disease. We report here a comparison of Fumouze hs-CRP turbidimetric method on Roche Diagnostics Hitachi 911 with Dade Behring BN II nephelemetric method. 134 samples were analysed. Within-run imprecision and between-run CV were good. Linearity was less satisfactory. Correlation study showed that without exceeding the maximum value of 6 mg/L, the hs-CRP method presented a good agreement with hs-CRP BN II method.

Troponin (I or T) has become the gold-standard marker in acute coronary syndromes during the last few years, as confirmed by a national survey realized within french clinical chemists, cardiologists and emergency practitioners. The importance of this marker and the heterogeneousness of circulating forms of troponin after myocardial necrosis fully justify international studies about standardization of this assay, which is a central bulk to reach a global market coherence. Checking analytical problems, although necessary, must be absolutely associated with an informed clinical interpretation. The knowledge of the crucial thresholds of each assay, the kinetic curves and the specificity limits of troponin assays allow the best use of their potential in diagnosis and prognosis together with an optimal patient care in very different clinical settings, in addition to others clinical and technical arguments. The quality improvement through successive generations of assay kits must nowadays persuade the physicians never to ignore a significant and valid troponin increase, which mainly reveals a cardiac injury, whatever its origin.

Immunofixation is widely used for monoclonal gammapathies identification and Bence Jones proteinuria research. In more of cases, interpretation is easy, but some difficulties persist. Five examples are presented and their causes are analysed; in our first case, seric immunofixation shows the problem generated by additives. These components are added to optimize antigen- antibody reaction but they can induce interferences; three cases of urinary immunofixation showing Bence Jones proteinuria with/or without complete monoclonal immunoglobulin are presented. The variability of immunsera avidity is sometimes a problem; a case of light chain disease associated with monoclonal IgA illustrate difficulties of interpretation when precipitin bands have nearly the same migration. These examples underline the great importance of regular controls of immunologic reagents. The use of two antisera with the same specificity but different origin is recommended in order to resolve difficulties with interpretation of immunofixation., (Copyright John Libbey Eurotext 20003.)