ABSTRACT
BACKGROUND: Since free light chain (FLC) is metabolized in the kidney, serum FLC concentration and kappa/lambda ratio are increased in patients with decreased renal function, even in the absence of monoclonal protein. In this study, we measured serum FLC levels to investigate the change in kappa/lambda ratios in relation to the severity of renal dysfunction. METHODS: Serum FLC concentrations were measured in 92 archived serum samples from patients diagnosed with chronic kidney disease using the Freelite assay (The Binding Site Group Ltd., UK), and kappa/lambda ratios were calculated. Serum creatinine levels were assayed to calculate estimated glomerular filtration rate (eGFR), and patients were divided into subgroups according to Kidney Disease Improving Global Outcomes (KDIGO) guidelines. We analyzed the difference in serum FLC levels and kappa/lambda ratios between subgroups. RESULTS: Serum FLC levels and kappa/lambda ratios increased depending on the severity of renal dysfunction. When patients were classified by setting cut-off value of eGFR as 60 mL/min/1.73 m2 (group A: eGFR ≥60 mL/min/1.73 m2, group B: < 60 mL/min/1.73 m2), the kappa/lambda ratio of group B was significantly higher than that of group A (group B: 1.60±0.46 vs. group A: 1.35±0.27, P=0.018). Serum FLC kappa/lambda ratios were within the previously determined renal reference interval (0.37–3.1). CONCLUSIONS: When interpreting results of serum FLC kappa/lambda ratio, renal function status should be considered in addition to hematological findings. If renal function deteriorates, a wider renal reference interval is preferred instead of the usual reference interval.
Subject(s)
Humans , Binding Sites , Creatinine , Glomerular Filtration Rate , Kidney , Kidney Diseases , Renal Insufficiency, ChronicABSTRACT
As gamopatias monoclonais resultam de hiperprodução de um único clone anormal de células plasmocitárias ou linfócitos B. O objetivo da avaliação laboratorial nas gamopatias é demonstrar a presença, a quantidade e o tipo de proteína anormal presente no soro e/ou na urina através do estudo do perfil protéico, quantificação das imunoglobulinas e cadeias leves e avaliação da proteinúria. Este artigo descreve as principais técnicas laboratoriais disponíveis, bem como suas indicações e limitações.
Monoclonal gammopathies result from an overproduction of a single abnormal clone of a plasma cell or B lymphocyte. The purpose of the laboratory protocols in these situations is to demonstrate the presence, the characterization and the concentration of an abnormal protein detected in serum and/or urine samples. The laboratory investigation is based on the electrophoretic protein profile, quantification of immunoglobulins, free light chains and proteinuria. This paper describes the major available laboratory methods as well their indications and limitations.
Subject(s)
Humans , Blood Protein Electrophoresis , Electrophoresis , Immunoelectrophoresis , Immunoglobulin kappa-Chains , Immunoglobulin lambda-Chains , Immunoglobulins , Paraproteinemias , Diagnostic Techniques and ProceduresABSTRACT
BACKGROUND: Immunoglobulins exist in the serum, mostly in a union type of heavy and light chains. Free light chain types exist in an extremely small quantity and are useful in the diagnosis and follow up of multiple myeloma, but are also increased in autoimmune diseases such as SLE. The aim of this study was to evaluate the usefulness of the serum free light chain in discriminating between monoclonal and polyclonal gammopathy. METHODS: Between January and June of 2003, we identified 15 patients with monoclonal gammopathy and 12 patients with polyclonal gammopathy on serum protein electrophoresis (SPEP) and immunofixation electrophoresis (IFE). We measured the serum concentration of the free light chain using Beckman Coulter IMMAGE(TM) analyzer with FREELITE(TM) reagents and calculated the kappa/lambda (kappa/lambda) ratio. We also measured the free light chain of 35 healthy controls to establish a reference range. RESULTS: The reference ranges established in this study were 4.97-12.84 mg/L for kappa light chains, 6.71-18.09 mg/L for lambda light chains, and 0.46-1.01 for the kappa/lambda ratio. The free light chains were abnormal in all 27 but 2 patients with polyclonal gammopathy on SPEP. The kappa/lambda ratio was abnormal in 12 of the 15 patients with monoclonal gammopathy and in none of the 12 patients with polyclonal gammopathy. CONCLUSIONS: Our results suggest that the kappa/lambda ratio can be a useful tool to discriminate between monoclonal and polyclonal gammopathy, especially in the case of vague SPEP results, or when monoclonal gammopathy is suspected in SPEP.