2. Urine M-protein ≥ 200 mg/24 hour, or In patients without detectable serum or urine M-protein, serum free light chain (SFLC) > 100 mg/L (involved light chain) and an abnormal serum k/l ratio or For IgA patients whose disease can only be reliably measured by serum quantitative immunoglobulin (qIgA) ≥ 7500 mg/L (7.5 g/L).