Serum anion gap in multiple myeloma patients

Abstract

The aim of this study was, first, to reconfirm the low serum anion gap (SAG) in multiple myeloma patients and, second, to propose the possible pathophysiologic mechanisms involved. We studied 20 patients with IgG multiple myeloma and 13 healthy subjects as controls. The SAG in multiple myeloma patients was significantly lower (p<0.001) compared with the controls. There was a significant inverse correlation between SAG and serum monoclonal immunoglobulin (r = 0.61, p<0.01). Serum sodium in multiple myeloma patients was lower than in the control population (p<0.001) and was negatively correlated to the amount of serum monoclonal protein (r = -0.44, p = 0.01). Serum albumin was significantly lower in the patients than in the normal controls (p<0.001). No correlation between the SAG and serum albumin was found in the patients' group. In conclusion, SAG is low in IgG multiple myeloma patients. This finding is directly associated with the amount of serum paraprotein which influences the value of serum sodium. Hypoalbuminemia could be an additional factor in the pathogenesis of this electrolyte disturbance.