Evaluation of the new Sebia free light chain assay using the AP22 ELITE instrument.

BACKGROUND: Serum kappa and lambda free light chains (FLC) are useful in the diagnosis, prognosis and monitoring of patients with monoclonal gammopathies. The Binding Site and Siemens were the only suppliers of kits for these analyses until recently, when Sebia introduced an enzyme-linked immunosorbent assay (ELISA) on an automated instrument, DAS AP22 ELITE. METHOD: Samples from routine analysis, controls and chronic kidney disease (CKD) patients were tested using the automated version of Sebia FLC ELISA with the AP22 ELITE and results were compared with Freelite on the SPA PLUS (The Binding Site). RESULTS: Sebia FLC ELISA showed a good performance using the AP22 ELITE. A concordance of 82% was found with the results obtained with Freelite. Sebia FLC is a reproducible assay, requiring less retesting than Freelite thanks to a broader range. Earlier findings that the results obtained are closer to the FLC monoclonal band measured by electrophoresis were confirmed. Higher kappa and lambda values obtained in CKD individuals were also shown, confirming that a kappa/lambda FLC ratio should be introduced by Sebia for CKD patients, as with The Binding Site. CONCLUSIONS: Sebia put forward new technology that automatically measures free light chains. This technique is suitable for routine use; however, the results cannot be used interchangeably with Freelite kits.

Comparison of plasma cardiac troponins T and I in chronically hemodialyzed patients in relation to cardiac status and age.

Cardiac troponins (cTnT and cTnI) are useful tools for risk stratification in patients with unstable angina. However, their value in patients with renal failure has been questioned. In this study, we determined cTnT and cTnI at 3-month intervals during 9 months in 97 chronic renal failure (CRF) patients treated with hemodialysis. cTnT was measured using a third generation immunoassay and cTnI by fluorimetric immunoassay with a detection limit similar to that of cTnT (0.01 microg/l). In the renal patients without coronary heart disease (CHD(-) group), cTnT was more frequently elevated above cut-off for acute myocardial infarction (AMI) (up to 21.6%) than cTnI (no patient). In the absence of CHD, cTnT levels were positively correlated to age, and more than half of the CHD(-) patients aged over 60 years had cTnT levels above the upper reference limit (URL) of 0.04 microg/l (0.059+/-0.042 microg/l). cTnI increased with age in parallel to cTnT but mean levels did not exceed the URL of 0.08 microg/l in the CHD(-) patients aged over 60 years (0.036+/-0.031 microg/l). In the patients with documented cardiac events (CHD(+)) we found higher troponin levels than in the CHD(-) patients of the corresponding age, but for cTnl the differences between CHD(+) and CHD(-) patients were significant in the patients aged < or =60 years only (0.049+/-0.054 vs. 0.019+/-0.018 microg/l, p<0.05). For cTnT, the differences between patients with and without coronary events also tended to be less important in the eldest patients. There was a significant correlation between cTnI and cTnT levels in the CHD(-) and in the CHD(+) groups. Changes in the plasma levels of cardiac troponins are common in hemodialysis patients in the absence of CHD, and advanced age appears to amplify these changes. The reason could be that most hemodialysis patients with advanced age have subclinical lesions and demonstrate release characteristics of troponins that compare to those in patients with symptomatic coronary events. Therefore, it will be important to analyze troponin elevations above the URL or above the cut-off concentration for AMI in asymptomatic renal patients in relation to prognosis.