Renal removal of low molecular weight proteins in myeloma and renal transplant patients.

Abstract

Abstract The renal handling of three low molecular weight (LMW) proteins was examined in 50 patients with monoclonal gammopathies and in 16 patients following renal homotransplantation. When expressed as per cent creatinine clearance the renal clearances of β 2 -microglobulin, free λ chains, and lysozyme were inversely proportional to the creatinine clearance in both groups of patients. The clearances of β 2 -microglobulin and λ chain correlated closely with each other and the rate of decline following successful transplantation was very similar for β 2 -microglobulin and free λ light chains. However, in myeloma patients with λ-chain excretion exceeding 400 mg. per day, the clearance ratio of β 2 -microglobulin to λ chain was inversely proportional to the daily λ-chain excretion. In some transplant patients the level of LMW proteins dropped before other evidence of renal function appeared, suggesting that renal catabolism may occur in the absence of urine formation. These findings suggest that β 2 -microglobulin and λ chain are handled by a common renal mechanism and that, in part, this mechanism may include peritubular secretion of protein.