Free Kappa: 3.3—19.4 mg/L
Free lambda: 5.71—26.3 mg/L
Kappa/Lambda ratio: 0.26—1.65
(In patients with renal failure, with no evidence of monoclonal proteins, a ratio of 0.37–3.1* can be used.)
*Hutchison C.A, et al. Serum free light chain measurement aids the diagnosis of myeloma in patients with severe renal failure. BMC Nephrology 2008; 9:11 doi: 10.1186/1471-2369-9-11
Elevated free kappa and/or lambda accompanied by a normal kappa/lambda ratio can be due to polyclonal activation or renal failure and should be interpreted with caution.
Long term studies of patients with MGUS and smoldering myeloma have shown a high biological variability of free light chain levels (CV 27.8%) in patients with stable disease (Katzmann et al. Clin Chem 2011: 1687-1692). Clinicians should take this into account when interpreting free light chain levels in their patients.
Method: Binding Site SPAPLUS (Turbidimetry) from 1/6/11.