[Markedly elevated serum fructosamine in a non-diabetic patient with IgA-kappa type multiple myeloma].

We reported a non-diabetic patient with IgA-kappa multiple myeloma whose serum fructosamine value was markedly elevated. The M-protein from this patient was shown to be conjugated to serum albumin confirmed by immunoelectrophoresis and immunofixation. The fructosamine activity was shown in the high molecular weight fraction by S-300 superfine gel chromatography. Although serum fructosamine values of other three non-diabetic patients with IgA type multiple myeloma were elevated, patients with IgG type multiple myeloma and primary macroglobulinemia had low or normal serum fructosamine values. These findings suggested that glycation of monoclonal IgA of multiple myeloma was much more increased than that of other types of immunoglobulins and monoclonal IgA in this patient was conjugated to serum albumin resulting in the elevated serum fructosamine.