LETTER TO THE EDITOR Plasma exchange after hematopoietic stem cell transplantation in multiple myeloma to reduce renal insufficiency Bone Marrow Transplantation (2008) 42, 767; doi:10.1038/bmt.2008.245; published online 11 August 2008 Hematopoietic cell transplantation (HCT) has been asso- ciated with the development of both acute and chronic kidney failure. 1 Although the requirement for dialysis following HCT is relatively uncommon (in the 2–5% range), it is associated with poor prognosis. The incidence of acute renal failure (defined as a 450% reduction in glomerular filtration rate) for those undergoing myelo- ablative autologous hematopoietic stem cell transplantation (AHSCT) has been reported as high as 20%. 2 Peripheral blood progenitor cells are cryopreserved using the cryo- protectant dimethyl sulfoxide (DMSO). Infusion of peri- pheral blood progenitor cells cryopreserved with DMSO has been associated with toxicities such as acute renal failure. 3 It has been reported that adverse events following infusions of cryopreserved hematopoietic stem cells is associated with the concentration of red blood cells in the infused specimen. 4 Therapeutic plasma exchange (plasmapheresis) removes large molecular weight substances from the plasma, including plasma-free hemoglobin. Plasma-free hemoglobin is the amount of hemoglobin free in plasma solution and is a result of red blood cell breakage or hemolysis. We report on two patients with multiple myeloma who underwent AHSCT after high-dose melphalan therapy who received plasma exchange to remove plasma-free hemoglo- bin related to the high hematocrit in the stem cell products. The first patient was a 69-year-old woman with immuno- globulin G (IgG) kappa multiple myeloma who received 3 days of stem cell infusions on day 0, þ 1 and þ 6. The hematocrit in the stem cell product ranged from 12 to 14%. On day þ 1, the patient’s creatinine increased from 1.6 to 3.2 mg/100 ml. Urine hemoglobin tested positive. The acute renal failure was felt to be due to the hemoglobinuria from the elevated hematocrit in the stem cell infusion. She underwent a 3 l plasma exchange following her second and third stem cell infusions on days þ 1 and þ 6. Plasma-free hemoglobin values pre- and post-plasma exchange and serum creatinine are reported in Table 1. The third day of stem cell infusion was delayed due to renal failure, which reached a peak creatinine of 3.8 mg/100 ml on day þ 2. The creatinine rose from 2.4 to 2.8mg/100ml following the third stem cell infusion, but the patient underwent plasma exchange on this day. At discharge on day þ 22, creatinine had returned to her baseline of 1.7 mg/100 ml. The second patient was a 69-year-old man with IgG kappa multiple myeloma who received 1 day of stem cell infusion. Because of the high hematocrit in the stem cell product of approximately 50%, and based on our experience with the first patient, the patient underwent plasma exchange approximately 4h after his stem cell infusion and a second plasma exchange on day þ 1 to decrease the likelihood of renal insufficiency secondary to the high hematocrit in the stem cell infusion product. There was no significant increase in serum creatinine during his hospitalization. To our knowledge, these are the only reported cases of the use of plasma exchange following AHSCT in patients with a high hematocrit in the stem cell product, to remove plasma-free hemoglobin and decrease the likelihood of renal insufficiency/failure secondary to the stem cell infusion. K Sullivan, S Jagannath, A Mazumder and DH Vesole Section of Hematology and Medical Oncology, Department of Medicine, St Vincent’s Hospital and Comprehensive Cancer Center, New York, NY, USA E-mail: dvesole@aptiumoncology.com References 1 Cohen EP. Renal failure after bone-marrow transplantation. Lancet 2001; 357: 6–7. 2 Parikh CR, Coca SG. Acute renal failure in hematopoietic cell transplantation. Kidney Int 2006; 69: 430–435. 3 Alessandrino P, Bernasconi P, Caldera D, Colombo A, Bonfichi M, Malcovati L etal. Adverse events occurring during bone marrow or peripheral blood progenitor cell infusion: analysis of 126 cases. Bone Marrow Transplant 1999; 23: 533–537. 4 Milone G, Mercurio S, Strano A, Leotta S, Pinto V, Battiato K et al. Adverse events after infusions of cryopreserved hematopoietic stem cells depend on non-mononuclear cells in the infused suspension and patient age. Cytotherapy 2007; 9: 348–355. Table 1 Serum creatinine and plasma-free hemoglobin values (mg %) pre- and post-plasma exchange Day Plasma-free Hgb pre-plasma exchange Plasma-free Hgb post-plasma exchange Creatinine 0 1.8 +1 460.00 1.90 3.2 +2 3.8 +3 3.6 +4 3.2 +5 2.6 +6 460.00 23.70 2.4 +7 2.8 +8 2.5 Bone Marrow Transplantation (2008) 42, 767 & 2008 Macmillan Publishers Limited All rights reserved 0268-3369/08 $32.00 www.nature.com/bmt