Serum beta 2-microglobulin levels in multiple myeloma and monoclonal gammapathy of undetermined significance: a clinical study of 55 patients.

Previous reports provided clear evidence that serum beta 2-microglobulin (beta 2m) is a marker highly correlated with the total mass of myeloma cells and suggested its use in the follow-up of patients with plasma cell tumors. Serum beta 2m levels were measured in 38 patients with multiple myeloma (MM), in 17 patients with monoclonal gammapathy of undetermined significance (MGUS) and in 32 normal control subjects. While statistically significant differences could be established between controls and both MM and MGUS patients, between patients with MM at stage III and patients with MM at lower stages as well as between patients with MGUS and patients with mostly advanced MM, it was not possible to statistically separate patients with MM at stage I from patients with MM at stage II, patients with untreated MM from patients with treated MM and, finally, patients with MGUS from patients with low cell mass MM. These results substantially confirm the already published data and lead to the conclusion that serum beta 2m determination is a useful test in the clinical management of monoclonal gammapathies, but it does not allow a differential diagnosis between benign and malignant forms of the disease.