Cystatin C Level as a Marker of Renal Function in Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) recipients have an increased risk of acute kidney injury (AKI) or chronic kidney disease (CKD). However, serum creatinine level may underestimate the prevalence of these renal complications because of decreased lean body mass or concurrent liver disease, which was frequently observed in a HSCT setting. Cystatin C measurement may be more sensitive for detecting impaired kidney function. We retrospectively reviewed the medical records of 70 HSCT (54 allogeneic and 16 autologous) recipients who had at least one chance to monitor serum cystatin C level during last 2 years in our institution, and evaluated cystatin C as a possible new marker which can predict subsequent renal dysfunction. The occurrence of AKI was defined by the RIFLE classification and CKD staging was based on KDOQI criteria. Of 70 transplant recipients, 20 patients developed AKI after median 50.5 days (range 0–283 days) after HSCT, while worsening CKD stage was observed in 21 patients during observational periods. Cystatin C level was not influenced by pretransplant disease status (P=0.153) or autologous transplant (P=0.311), but significantly elevated after allogeneic transplantation (P<0.001). Multivariate analysis disclosed that the use of calcineurin inhibitor was a major cause of cystatin C elevation (Odds ratio 7.00, P=0.045). There was also a strong inverse correlation between cystatin C and estimated GFR (r=−0.684, P<0.001). Proportional hazard modeling analysis revealed that pretransplant cystatin C level (>0.90mg/l) and the episode of AKI after transplantation were a great risk for substantially worsening CKD stage (Hazard ratio 4.21 and 16.0, P=0.042 and P<0.001, respectively). Cystatin C measurement could be a useful clinical tool to identify HSCT recipient at increased risk for CKD.