Serum beta 2-microglobulin at remission and relapse in patients with multiple myeloma.

Serum beta 2-microglobulin (S-beta 2m) was determined before treatment in fifty patients with multiple myeloma (MM), twenty-two of which had pure Bence Jones (BJ) myeloma. S-beta 2m was related to clinical stage before, but not after, a correction of S-beta 2m values for co-existent raised S-creatinine values (greater than 106 mumol 1-1). However, S-beta 2m as well as corrected beta 2m was a parameter of prognostic value. The median expected survival time was 14 months at S-beta 2m values greater than 8.0 mg 1(-1) and 56 months at values less than 3.5 mg 1(-1). A response to treatment was associated with a decrease of S-beta 2m and a stationary course with unchanged values, whereas a relapse or progressive disease was connected with an increase. In 'beta 2m producers', i.e. patients with a clear initial high S-beta 2m, serial determinations are of value for monitoring patients with MM. In particular, this is the case in BJ myelomas, as they lack a quantifiable serum M-component. With respect to beta 2m no difference was found between BJ and other patients with MM.