Serum standardized free light-chain (sFLC) ratio distribution. (A) Patients were divided based on multiple myeloma (MM) types, such as immunoglobulin (Ig) G, IgD, or IgA, and light-chain types and sFLC ratio values were compared among groups. (B) Similarly, sFLC ratio values at diagnosis were compared based on Revised International Staging System (R-ISS) stages. According to the normal range of the sFLC ratio, patients were divided based on normal or abnormal values at diagnosis and (C) percentage of bone marrow (BM) plasma cells or (D) the ratio between BM plasma cells and residual hemopoiesis were compared among groups. Data are shown as mean + SD. * p < 0.05.