{"id":"kappa-free-light-chains","name":"Free Kappa Light Chains, Serum","shortName":"Free kappa","aliases":["Kappa Free Light Chains","Free Kappa","Kappa Light Chains, Free","Free Light Chain, Kappa","Kappa FLC","Free Kappa Light Chains","Serum Free Kappa","FLC Kappa","Kappa Free Light Chain, S","Kappa Qnt Free Light Chains"],"abbreviations":["Kappa FLC"],"loinc":[{"code":"36916-5","primary":true},{"code":"104544-2","primary":false},{"code":"80515-0","primary":false}],"specimen":"serum","units":[{"ucum":"mg/L","display":"mg/L"},{"ucum":"mg/dL","display":"mg/dL"}],"referenceRanges":[{"population":"Adults","low":3.3,"high":19.4,"unit":"mg/L","unitDisplay":"mg/L","note":"Freelite (The Binding Site) interval from healthy adults aged 21 to 90 with normal kidney function (Katzmann 2002). ARUP prints 3.30–19.40 mg/L and the University of Iowa Hospitals prints 3.3–19.4 mg/L. Other methods differ: the manufacturer interval for Siemens N Latex FLC is 6.7–22.4 mg/L, and Mayo Clinic Laboratories prints 0.61–4.02 mg/dL (6.1–40.2 mg/L) for its turbidimetric method. Kappa rises as kidney function falls: among about 6,500 people with eGFR below 60 and no sign of a monoclonal protein, 60% were above 19.4 mg/L (iStopMM). Use the range printed on your own report.","sources":[{"title":"Serum reference intervals and diagnostic ranges for free kappa and free lambda immunoglobulin light chains: relative sensitivity for detection of monoclonal light chains","url":"https://pubmed.ncbi.nlm.nih.gov/12194920/","publisher":"Clinical Chemistry","year":2002},{"title":"Kappa/Lambda Quantitative Free Light Chains with Ratio, Serum (test 0055167)","url":"https://ltd.aruplab.com/Tests/Pub/0055167","publisher":"ARUP Laboratories"},{"title":"Kappa-Lambda Quant Free Light Chain Ratio, Blood","url":"https://www.healthcare.uiowa.edu/path_handbook/handbook/test1117.html","publisher":"University of Iowa Hospitals & Clinics Pathology Handbook"},{"title":"Immunoglobulin Free Light Chains, Serum (test FLCS)","url":"https://www.testcatalog.org/show/FLCS","publisher":"Mayo Clinic Laboratories (Extended Catalog)"},{"title":"Comparison of Freelite and N-Latex serum free light chain assays: a critical review","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8340501/","publisher":"Biochemia Medica","year":2021},{"title":"Defining new reference intervals for serum free light chains in individuals with chronic kidney disease: Results of the iStopMM study","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9470548/","publisher":"Blood Cancer Journal","year":2022}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"A small antibody piece (kappa type) made by plasma cells. It is read with lambda, the ratio and your kidney function.","url":"https://bloodtesttracker.com/markers/kappa-free-light-chains","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}