Free light chains are nephrotoxic and may be the cause of unexplained renal impairment. Assays for kappa (κ) and lambda (λ) free light chains (FLC) are an important tool in the screening for, or ruling out of, Multiple Myeloma. The N Latex FLC assay for Free Light Chains uses monoclonal antibodies for detection and is reported to have no false positive κ/λ ratios in patients with renal impairment4-6. Without these false positives, patients may avoid unnecessary, painful, and costly bone marrow biopsies.
- Serum free light chain assessment is used in the diagnosis and monitoring of patients with monoclonal gammopathies, such as Multiple Myeloma.
- Use of FLC assays is appropriate to rule out Myeloma as an underlying cause of renal impairment.
- Use of polyclonal assays for FLC kappa and lambda in patients with renal impairment such as Chronic Kidney Disease or Acute Kidney Injury can lead to elevated and falsely abnormal κ/λ ratio1-3.
- The false positive rate using these polyclonal FLC assays in patients with renal impairment is between 8 and 36% 2,3.
- Abnormal FLC κ/λ ratios often trigger a referral to a hematologist/oncologist for full diagnostic work-up for multiple myeloma, which includes a bone marrow biopsy.
