What happens to monoclonal FLC concentrations when patients develop renal impariment?
As patients develop renal impairment the concentrations of κ and λ polyclonal serum FLCs increase. This is associated with an increase in the monoclonal FLC but the κ/λ ratio will also increase slightly because of the relative reduction in clearance of κ molecules (Chapter 11.2). However, changes in the κ/λ ratio are a better guide to changes in clinical status when glomerular filtration rates are changing than the concentrations of the monoclonal FLC. Changes in the concentrations of creatinine or cystatin C should be assessed, under these circumstances, in order to provide an independent assessment of renal function and a correction factor for the κ/λ ratios.
