RESUMO
BACKGROUND: The detection of monoclonal immunoglobulins (MIg) is a key element in the diagnosis of monoclonal gammopathies. METHODS: Here we report two cases of high concentration serum IgM-kappa MIgs (6.4 g/L and 6.8 g/L) not detected with capillary electrophoresis (CE). A systematic literature search was conducted to assess the sensitivity of CE to detect MIgs. RESULTS: The CE sensitivity to detect MIgs did not exceed 0.9 to 0.95 compared to immunofixation as standard. On the one hand, MIgs with blood concentrations below 1 g/L may be hidden by other serum proteins. On the other hand, some MIgs of high concentrations are not detected due to their insolubility in the electrophoresis buffer. CONCLUSIONS: Performing a second SPE with agarose gel electrophoresis method or modifying buffer properties may reveal some MIgs not detected by a first SPE alone.
