Validation of free light chain reference intervals and their association with age and eGFR

To establish reference intervals (RIs) for serum free κ and λ light chains and the κ/λ ratio (FLCR) in healthy adults in China, and to evaluate the influence of age and estimated glomerular filtration rate (eGFR) METHODS: A total of 549 healthy adults with eGFR > 90 mL/min/1.73 m² were enrolled. FLCs were measured using nephelometric assays (Goldsite Diagnostics). RIs of κ-FLC and λ-FLC were calculated based on the 2.5th to 97.5th percentiles(95 % interval),and FLCR was calculated on 100 % of this cohort. Additional subgroup analyses included individuals with reduced eGFR(60-89 mL/min/1.73 m²)to assess the association between renal function and FLC concentrations. Spearman correlation and regression analyses were used to assess relationships between FLCs, FLCR, age, and eGFR.

This study RIs were determined: κ-FLC 4.27-35.05 mg/L, λ-FLC 12.61-34.09 mg/L, FLCR 0.15-1.58. All FLC parameters were inversely correlated with eGFR(p < 0.001) and increased with age(p < 0.001) CONCLUSIONS: RIs derived from other assays or cohorts may not be directly applicable to all settings. The influence of age and renal function in clinical practice, FLC results should be interpreted in combination with relevant clinical and laboratory information.