title: N Latex FLC serum free light-chain assays in patients with renal impairment.
abstract: 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 BNII system and compared with controls without renal impairment.
  
  
  RESULTS
  Both κFLC and λFLC concentrations increased with the N Latex FLC and the Freelite assays with each increment in CKD stage. No difference was found in FLC κ concentrations between the two methods. In patients with renal failure, N Latex FLC detected higher concentrations of λFLC (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 κ/λ ratios in patients with CKD for the two tests. The Freelite κ/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 κ/λ ratio exceeding the N Latex reference limits for healthy controls (0.31-1.56). The N Latex FLC κ/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 κ/λ ratio in patients with renal failure did not differ from the reference limits for healthy controls.
authors.forename: Joannes F M
authors.initials: JF
authors.lastname: Jacobs
authors.forename: Rein M J
authors.initials: RM
authors.lastname: Hoedemakers
authors.forename: Elisa
authors.initials: E
authors.lastname: Teunissen
authors.forename: Henk
authors.initials: H
authors.lastname: Te Velthuis
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D007840:Latex; D051436:Renal Insufficiency, Chronic / Q000097:blood*; D012189:Retrospective Studies
chemical_list: D007147:Immunoglobulin Light Chains; D007840:Latex