Implications for Monitoring Monoclonal Gammopathies

clinically stable monoclonal gammopathy to deter-mine the total variation of serumM-spikes [serumpro-tein electrophoresis (SPEP)], urine M-spikes [urine protein electrophoresis (UPEP)], and monoclonal se-rum free light chain (FLC). METHODS: Patients to be studied were identified by (a) no treatment during the study interval, (b) no change in diagnosis and5 g/L change in serumM-spike over the course of observation; (c) performance of all 3 tests (SPEP,UPEP, FLC) in at least 3 serial samples that were obtained 9 months to 5 years apart; (d) serumM-spike 10 g/L, urine M-spike200 mg/24 h, or clonal FLC 100 mg/L. The total CV was calculated for each method. RESULTS: Among the cohort of 158 patients, 90 ha