An increasingly abnormal serum-free light chain ratio may be a harbinger of symptomatic myeloma. The temporal changes in monoclonal immunoglobulin level and involved serum free light-chain ratio (iFLC) are shown for 6 patients with intact immunoglobulin myeloma (A-F) and 1 patient with light-chain myeloma (G). The M-Ig is plotted on the outside axis and the iFLC ratio on the inside axis. The iFLC ratio is expressed as λ/κ for patients with clonal λ MM. For the 1 patient with light-chain myeloma (G), the involved sFLC is plotted on the outside axis and the involved free light-chain ratio is plotted on the inside axis.