{"id":"kappa-lambda-ratio","name":"Free Kappa/Lambda Light Chain Ratio","shortName":"Kappa/lambda ratio","aliases":["Kappa/Lambda Ratio","K/L Ratio","Kappa/Lambda Free Light Chain Ratio","FLC Ratio","Free Light Chain Ratio","Free Kappa/Lambda Ratio","Serum FLC Ratio","Free Light Chain Ratio (Kappa/Lambda)","Kappa/Lambda FLC Ratio"],"abbreviations":["K/L ratio","FLC ratio"],"loinc":[{"code":"48378-4","primary":true},{"code":"104546-7","primary":false},{"code":"80517-6","primary":false}],"specimen":"calculated","units":[{"ucum":"{ratio}","display":"ratio"}],"referenceRanges":[{"population":"Adults","low":0.26,"high":1.65,"unit":"{ratio}","unitDisplay":"ratio","note":"Freelite (The Binding Site) interval for people with normal kidney function. Katzmann (2002) called it a diagnostic interval; ARUP and the University of Iowa Hospitals both print 0.26–1.65. Other methods differ: the manufacturer interval for Siemens N Latex FLC is 0.31–1.56, and Mayo Clinic Laboratories prints 0.57–2.45 for its turbidimetric method. A 2025 study proposed 0.686–2.10 for people of African ancestry with normal kidney function. 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":"Serum free light chains in a racially diverse population including African Americans and populations from South Africa","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC11867122/","publisher":"Blood","year":2025}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"Compares kappa with lambda free light chains. A lopsided ratio can be a clue to a plasma cell condition, but kidney disease also shifts it.","url":"https://bloodtesttracker.com/markers/kappa-lambda-ratio","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}