Increased Monoclonal Components: Prevalence in an Italian Population of 44 474 Outpatients Detected by Capillary Electrophoresis

BACKGROUND: Identification, quantification and typing of M-Proteins (MP) play an important role in the diagnosis, classification and monitoring of monoclonal gammopathies both of malignant origin (eg. Multiple Myeloma) and of unknown origin. Previous evidence attests that MGUS (Monoclonal Gammopathy of Undetermined Significance) detected by agarose gel electrophoresis has a prevalence of 3.2% in the general population. Therefore, our study aimed to verify this data by means of capillary zone electrophoresis (CZE). METHODS: CZE was performed to evaluate the prevalence of M-Protein (MP) in 44.474 consecutive outpatients of all ages with a prescription for serum protein electrophoresis over a 2-year period (2008 and 2009). All MPs that were identified were then typed by immunofixation electrophoresis on agarose gel (IFE). RESULTS: In subjects aged over 50 (23.408, i.e., 52.6% of the whole cohort) MP ≤30 g/L (MGUS) was identified in 6.0% of cases, with a frequency nearly double than that previously reported. The population was then divided into ten-year age groups: the 71–80 age group had the highest percentage of MP (29%), followed by 61–70 (27%), 51–60 (18%), 81–90 (12%), 41–50 (8%), 31–40 (3%), >90 (2%) and <30 (1%). The frequency of MP types (IFE) was the same in each age group, with IgG Kappa being the most represented class. CONCLUSIONS: According to the high MGUS prevalence observed in this study, these results may be useful especially for general practitioners, because the identification even of small MP (analytical sensitivity: 0.5 g/L) may help optimize clinical management.