Involved FLC-ratio year by year prior to multiple myeloma diagnosis.* In approximately half the study population, the involved FLC-ratio levels showed a year-by-year increase prior to multiple myeloma diagnosis (red dashed line), whereas the other half did not (blue solid line). *Including all subjects with an abnormal kappa-lambda FLC-ratio. Serum samples with a kappa-lambda FLC-ratio less than 0.26 and more than 1.65 were defined as having an “involved lambda” and “involved kappa” FLC-ratio, respectively. For samples with an involved lambda FLC-ratio, the involved FLC-ratio was computed by diving lambda with kappa. For samples with an involved kappa FLC-ratio, it was computed by dividing kappa with lambda. All samples with a kappa-lambda FLC-ratio within the normal range (reference: 0.26-1.65) were excluded from these analyses.