How would you approach IgM kappa MGUS paraproteinemia with a rising free light chain ratio?  

If a patient with minimal <1.5 gr/dL IgM kappa paraprotein undergoing surveillance has a slight increase in their kappa light chain with an abnormal ratio, and no signs of WM/LPL/amyloidosis or demyelinating polyneuropathy, would you consider additional workup? If so, what workup would you do given the unique nature of IgM MGUS rarely progressing to MM?