N Latex FLC serum free light-chain assays in patients with renal impairment

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. 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. 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