[Serum beta-2-microglobulin in multiple myeloma. Practical value].

: The concentration of serum, beta-2-microglobulin (S beta 2m) and the ratio measured S 2m/theoretical S beta 2m M/TH were evaluated in 69 patients with multiple myeloma (MM) and compared with healthy subjects and with patients with a benign monoclonal gammapathy. The concentration of S beta 2m and the ratio S beta 2m M/TH are higher in multiple myeloma than in controls and are strongly correlated with the plasma cell mass On the other hand, no difference was noted concerning the S beta 2m and the ration S beta 2m M/TH between benign monoclonal gammopathy and multiple myeloma at stage I of Durie and Salmon. Under chemotherapy, the variations in concentrations of S beta 2m and of the ratio S beta 2m M/TH are strongly correlated with those of the tumour mass. Beta 2m is not very useful for the differential diagnosis between benign monoclonal gammapathy and multiple myeloma. Beta 2m is very useful in the prognosis of MM, permitting one to assess accurately the tumour mass and the response to treatment, particularly in cases of deficiency of the usual markers.