Acute Kidney Injury after Hematopoietic Stem Cell Transplantation

OBJECTIVE: The aim of this study was to closely follow up renal functions in patients for a period of 100 days after hematopoietic stem cell (HSC) transplantation in order to be able to determine the incidence, possible causes and risk factors of acute kidney injury (AKI). MATERIAL and METHODS: Forty eight allogeneic (%73.8) and 17 autologous (%22.6) HSC transplantation patients were included in the study. All patients were followed for the signs and symptoms of AKI for a period of 100 days after the HSC transplantation. All HSC transplantation patients were included in the study except those with end-stage renal disease. Complete blood count and biochemical parameters were measured in all patients. Twenty-four hour urine samples were collected at the beginning and at +7, +14, +21, +30, +60 and +90 days after the HSC transplantation. The urine samples of the 24 hour collected urine were analyzed to calculate creatinine clearance and to obtain proteinuria. All etiologic factors which may be a cause for AKI were recorded during the follow up period. RESULTS: It was found that AKI was more common in allogeneic HSC transplantation than in autologous HSCT patients. It was determined that serum creatinine levels were at least doubled in 24 of 65 HSC transplantation patients. All of these 24 patients were allogeneic HSC transplantation patients. Creatinine clearence values were decreased by more than 50% in 12 patients, three of whom were autologous HSC transplantation patients while serum creatinine levels were not doubled in these patients. In conclusion, AKI were diagnosed in 36 of the 65 patients (55.38%). RIFLE classifi cation is an index which has been developed to evaluate the acute failure in renal functions. According to the RIFLE classifi cation, the percentage of the AKI development was 78.5%. There were 18 (27.7%), 20 (30.8%) and 13 patients (20.0%) in ‘Risk’, ‘Injury’ and ‘Failure’ groups respectively. There was no difference between the patients developing AKI nor in terms of age and gender. There was no difference between the patients developing AKI nor with regard to the number of the CD34+ stem cells. Additionally, no difference was found in proteinuria development and its severity. There was no relation between proteinuria and AKI development. Basal serum creatinine levels were lower in AKI developing patients (p<0.05) and basal creatinine clearance was higher (p<0.05). Although cyclosporine levels were higher in AKI developing patients, the difference was not statistically meaningful (p>0.05). Renal function tests returned to normal ranges in 23 of the 36 AKI developing patients (63.9%). On the other hand, while serum creatinine levels returned to normal values, creatinine clearance slowly decreased in four patients. However, creatinine clearance levels were increased and serum creatinine levels decreased in four patients. CONCLUSION: The incidence of AKI in HSC transplantation patients was found to be quite high. Not only should serum creatinine levels, but also creatinine clearance estimation, determined by collecting 24 hour urine, be used for the aim of evaluating renal functions in these groups of patients. Measuring solely serum creatinine levels may lead to overlook the patients with decreased creatinine clearance in HSC transplanted patients. It should be emphasized that timely diagnosis has great importance to prevent the progression of AKI.