Serum beta 2-microglobulin in patients with monoclonal gammopathies.

Beta-2-microglobulin concentrations were determined in serum samples from 45 patients with benign and malignant monoclonal gammopathies. In the group of patients suffering from multiple myeloma or Waldenström macroglobulinemia the mean beta 2-microglobulin level was significantly higher than in the group with monoclonal gammopathy of undetermined significance. Values above 3 mg/L were highly indicative of a neoplastic process and were observed in all the Waldenström patients and in greater than 90% of myeloma patients. No significant correlation was noticed between beta 2-microglobulin and monoclonal protein levels in any of the groups examined.