Serum results before the diagnosis of myeloma. Positive results are shown by ●, ■, ▲, ×, and +. Samples that were negative for all 3 tests (ie, no M-Ig present) are shown by ○. ● represents positive SPEP, IFE, and sFLC assay; ■, positive SPEP and immunofixation; ×, positive sFLC assay only; ▲, positive IFE only; and +, serum-free light assay and immunofixation. The color indicates the myeloma isotype: red represents IgG; green, light-chain/nonsecretory; and blue, IgD. Because the sFLC assay was not available at diagnosis, all patients are depicted with ● at the time of diagnosis for clarity.