Capillarys 2 Flex Piercing: Analytical performance assessment according to CLSI protocols for HbA1c quantification.

HbA1c is used for monitoring diabetic balance. In this paper we report an assessment of the analytical performances of Capillarys 2 Flex Piercing (C2FP) for HbA1c measurement using CE (Capillary Electrophoresis). CLSI (Clinical and Laboratory Standard Institute) protocols are used for the evaluation of apparatus performances: precision, linearity, method comparison, trueness and common interferences. HbA1c CVs average in intra-assay was 1.6% between run imprecision CV ranged from 0.1 to 1.8%. The linearity was demonstrated between 4.7 and 15.0%. The comparison study revealed that Bland Altman plot mean difference was equal to -0.03 (CI 95% (-0.05 to -0.0003)) and Passing-Bablok regression intercept was -0.05, CI95%(-0.13 -  -0.05); slope: 1.00, CI95%[1.00-1.01]. A strong correlation (r > 0.99) was proved. No significant effects of hemoglobin variants were seen with CE on HbA1c measurement. No problem related to sample-to-sample carry over was noted. No interferences of LA1c and cHb were observed. CE allowed quantification of HbA1c even at low level of total hemoglobin (40 g/L) in contrast to HPLC. Furthermore, this analyzer offered the opportunity of quantifying the HbA2 simultaneously with HbA1c . This evaluation showed that C2FP is a convenient system for the control of diabetes and the detection of hemoglobinopathies.

Evaluation of free thyroxine determination based on one-step fluorometric immunoassay technique and the suboptimal concordance with two-step immunoassay.

Free thyroxine (FT4) quantification is continuing to be a concern. The purpose of the following study was to evaluate the analytical performance of Tosoh AIA900 based on a one-step technique and its comparison to Access 2 (two-step technique) over different clinical contexts (euthyroid, thyroid disorders, uncontrolled diabetes, renal failure and pregnancy). The protocol established by the French society of Clinical Biology was used to evaluate: imprecision, limit of detection, trueness, linearity, interferences and method comparisons. Within-run variation of 3.1%, 5.7% and 4.4% were found for the low, medium and high controls, respectively. Between-run was 5.8% for low control, 5.7% for medium control and 7.1% for high control. Common interferences did not affect one-step immunoassay FT4 results. The linearity was checked up to 86 pmol/L. The limit of detection was 5.5 pmol/L. The concordance correlation coefficient (CCC) showed a low agreement (0.6) between both methods. Bland-Altman plot revealed that AIA 900 one-step immunoassay technique provides a significant higher values ((+2.8 ±â€¯2.7 pmol/L;p < 0.0001). The Passing-Bablok regression demonstrated both proportional and systematic differences in comparison to Access 2. The lowest association was noted in subjects with impaired renal function (CCC = 0.27). At the time of the study, the results of on-step immunoassay are not directly comparable with Access 2.