Comparison of serum beta 2-microglobulin and 24 hour urinary creatinine clearance as a prognostic factor in multiple myeloma.

A new staging system for multiple myeloma (MM) has utilized serum concentrations of beta2-microglobulin (Sbeta2M) and albumin as important prognostic factors for survival. Since Sbeta2M is an indicator of glomerular filtration rate, we compared the prognostic values of Sbeta2M and 24-hr urinary creatinine clearance (Ccr) in patients with MM. We retrospectively reviewed the records of 170 MM patients from January 1996 to November 2003 whose 24-hr urinary Ccr was available at the time of diagnosis. We found that pretreatment Sbeta2M was inversely related to Ccr (Spearman's correlation coefficient=-0.787). In univariate analysis, the hazard ratio (HR) of death was 1.043 (p<0.001) for Sbeta2M and 0.985 (p<0.001) for Ccr. Multivariate analysis showed that Sbeta2M (HR 1.030, p=0.010) and Ccr (HR 0.993, p=0.059) were significant prognostic factors in patients' survival. In conclusion, 24-hr urinary Ccr may be utilized for staging of patients with MM.