[A study of the significance of serum beta 2-microglobulin levels in patients with multiple myeloma--analyzes as a marker of renal dysfunction and as a marker of tumor cell mass].

Renal involvement known as a myeloma kidney is often observed in patients with multiple myeloma (MM). This complication has been recognized as one of the most important prognostic factors in this disease. Serum beta 2-microglobulin (S beta 2-m) has been also recognized one of the prognostic factor that reflects both a glomerular infiltration rate and a volume of neoplastic cells, because beta 2-m usually can be produced by the neoplastic lymphoid cells. To clarify the significance of the S beta 2-m in MM, we compared S beta 2-m levels and the clinical stage, with another clinical parameters for renal function such as 24 hr creatinine clearance (24 hr Ccr), N-acetyl-beta-glucosaminidase (NAG) levels in urine and serum alpha 1-microglobulin (S alpha 1-m) levels. The elevated S beta 2-m levels were commonly observed not only in patients with stage IIIB, but also in stage IA, IIA and IIIA (76%) who have normal renal function judged by the serum nitrogen or creatine levels. S beta 2-m levels correlated with 24 hr Ccr the most, then correlated with S alpha 1-m levels and less correlated with NAG levels in urine. Although a single elevation of S beta 2-m levels with other normal findings of renal parameters was found only in three out of 30 MM patients, the S beta 2-m levels in these patients did not change after the chemotherapy which had led to the diminution of serum M-protein. Together with these results, it was suggested that the S beta 2-m levels mainly reflect the renal dysfunction even if it stays in the subclinical stage, and reflect less the number of neoplastic cells in MM patients.