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Amsterdam-Zuidoost, Netherlands

Jacobs J.F.M.,Radboud University Nijmegen | Hoedemakers R.M.J.,Robert Bosch GmbH | Teunissen E.,Sanquin Reagents | Te Velthuis H.,Sanquin Research and Landsteiner
Clinical Chemistry and Laboratory Medicine | Year: 2014

Background: The aim of this study was to establish ranges for N Latex free light-chain (FLC) monoclonal-based nephelometric assays in patients with renal impairment. Methods: In this retrospective study, serum samples from 284 patients with chronic kidney disease (CKD) stages 1-5 were measured with N Latex and Freelite™ FLC reagents on the Siemens BN™II system and compared with controls without renal impairment. Results: Both kFLC and λFLC concentrations increasedwith the N Latex FLC and the Freelite™ assays with each increment in CKD stage. No difference was found in FLC ? concentrations between the two methods. In patients with renal failure, N Latex FLC detected higher concentrations of ?FLC (CKD5 median, 128 mg/L; 95% range, 43-302) compared with Freelite™ (89.5 mg/L, 35-197) (p < 0.0001). This resulted in significantly different k/λ ratios in patients with CKD for the two tests. The Freelite™ k/λ ratio in the CKD5 group (median, 1.22; min-max, 0.22- 2.70) was significantly increased compared with healthy controls (p < 0.0001), and several individual samples were outside the reference range for healthy controls (0.26- 1.65). In contrast, none of the 284 patients with CKD had an FLC k/λ ratio exceeding the N Latex reference limits for healthy controls (0.31-1.56). The N Latex FLC k/λ ratio in the CKD5 group (0.69, 0.32-1.54) was significantly lower compared with the control group (p < 0.0001). Conclusions: These findings demonstrate that the N Latex FLC k/λ ratio in patients with renal failure did not differ from the reference limits for healthy controls. Source

Te Velthuis H.,Sanquin Reagents | Te Velthuis H.,Sanquin Research | Knop I.,Sanquin Reagents | Stam P.,Sanquin Reagents | And 9 more authors.
Clinical Chemistry and Laboratory Medicine | Year: 2011

Background: High serum concentrations of monoclonal free light chain (FLC) kappa or lambda are markers of plasma cell dyscrasia. Methods: We developed new, latex-enhanced, specific nephelometric assays based on monoclonal antibodies for the determination of FLC kappa and lambda in serum, EDTA plasma and Li-heparin plasma for use on the Siemens BN™ systems. Results: Reference ranges were determined from 369 samples: FLC kappa 6.7-22.4 mg/L, FLC lambda 8.3-27.0 mg/L and kappa/lambda ratio 0.31-1.56. Protection from falsely low results due to antigen excess is obtained with a built-in pre-reaction in the assay protocols. Lot-to-lot consistency between three different lots of reagent, calibrators and supplementary reagent lots showed normalized differences <7.5%. The reproducibility of serum samples varied between 4% and 7%. The method comparison with Freelite™ assays showed normalized differences of 19.7%, 32.7% and 21.7%, respectively, for FLC kappa, lambda and ratio, correlations of 0.94, 0.77 and 0.73, and concordance rates of 99.2%, 94.2% and 95%. Conclusions: N Latex FLC demonstrates high precision, good lot-to-lot consistency and freedom from a high-dose hook effect. The method comparison between Freelite™ and the N Latex FLC assays showed good clinical concordance. Further studies need to reveal the clinical value of the new FLC assays. © 2011 by Walter de Gruyter Berlin Boston. Source

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