Cluster 297: creatinine mg dl equal renal cr umol level plasma norms Cluster 671: creatinine uln institutional equal cohort baseline greater age biopsy plasma Cluster 1134: creatinine mg dl serum umol equal registration days prior renal Cluster 1338: albumin dl equal hypoalbuminemia screening greater plasma level levels low Cluster 1386: plasma bone marrow cells dl clonal myeloma mg lesions serum