新居 春菜

Renal failure is a frequent complication in patients with multiple myeloma. Immunoglobulin free light chains (FLCs) form casts in the distal tubules, resulting in renal obstruction, and are also directly toxic to proximal renal tubules. Removal of FLCs contributes to renal recovery. High cut-off (HCO) membrane Theralite2100, protein leaking dialyzer PES210D alpha, plasma separator Evacure1A20 and beta(2) microglobulin adsorption column LixelleS-35 were compared in their FLC removal rate. Dialysis using Theralite2100 or Evacure1A20, diafiltration using PES210D alpha and adsorption using LixelleS-35 were performed in an in vitro circuit. The highest removal rate was obtained by Theralite2100 dialysis among the four blood purification methods. Albumin loss was also the greatest in Theralite2100 dialysis. The removal content of FLCs per 1 g albumin loss was better in PES210D alpha diafiltration. The removal rate of FLCs by Evacure EC1A-20 dialysis was the third highest. Adsorption of FLCs by the beta(2) microglobulin adsorption column Lixelle S-35 was confirmed. In conclusion, Theralite2100 dialysis was the best in removal of FLCs. PES210D alpha diafiltration can remove FLCs with smaller loss of albumin.

Aggressive removal of circulating free light chains (FLC) by blood purification accompanied by chemotherapy is a promising approach for the treatment of acute renal failure due to myeloma cast nephropathy. Plasma exchange has been performed to remove serum FLC; in order to examine an alternative strategy we performed hemodiafiltration using protein-leaking dialyzers for the treatment of dialysis-dependent acute renal failure due to myeloma cast nephropathy. In the first case with kappa-light chain cast nephropathy, the pre-treatment serum creatinine was 9.65 mg/dL, and the serum kappa-FLC was 27 100 mg/L. Plasma exchange or hemodiafiltration was performed from Monday to Friday during the first several weeks. Chemotherapy was started with high-dose dexamethasone and then switched to bortezomib plus dexamethasone. The mean removal rates of kappa-FLC were 45.8% (one plasma volume) and 66.9% (one-and-a-half plasma volumes) by plasma exchange. The removal rates of kappa-FLC by hemodiafiltration (66.9%, FB210UH beta; 71.6%, PES210D alpha; 75.2%, FXS220) were comparable to those by plasma exchange. In the second case with lambda-light chain cast nephropathy, the pre-treatment serum creatinine was 4.14 mg/dL, and the serum lambda-FLC was 4140 mg/L. The mean removal rates of lambda-FLC were 60.2% (FXS140) and 64.2% (FB210UH beta) by hemodiafiltration. Both cases became dialysis-independent. The combination of an intense blood purification regimen and bortezomib plus dexamethasone therapy appears to be an efficient approach to renal recovery. Hemodiafiltration using protein-leaking dialyzers could become an alternative to plasma exchange as a method of removing FLC.