[Early identification of acute kidney injury after hematopoietic stem cell transplantation by the measurement of urinary biomarkers]

Myeloablative (m-allo) hematopoietic stem cell transplantation (SCT) involves a great risk of acute kidney injury (AKI). We assessed whether or not early elevation of urinary biomarkers is useful for identifying high-risk patients for AKI.A prospective cohort study was conducted in 40 patients (46.0+/-12.5 years, eGFR 96.1 +/- 25.3 mL/min/1.73 m2) who received m-allo SCT in our hospital. We measured urinary biomarkers such as N-acetyl-beta -glucosaminidase (NAG), beta2 microglobulin (beta 2M), alpha microglobulin ( alpha1M) before conditioning therapy, on the day of SCT and both days 7 and 14 after SCT. AKI was defined as a decrease in eGFR within 100 days after SCT, and classified based on the RIFLE criteria. Discriminative sensitivity of urinary biomarkers was estimated using area under receiver operating characteristic (AuROC) curve analysis.AKI occurred in 28 cases(70 %): risk was 25.0 %, injury was 17.5 %, failure was 22.5 % and loss was 5.0 %, respectively. Only 4 cases with AKIor = injury that occurred less than 40 days after SCT died within 100 days after SCT. Thus, this level of AKI was denoted as"severe AKI"and targeted for early identification. Values of all urinary biomarkers increased gradually after the conditioning therapy, and both NAG and alpha 1M values at day 7 became significantly higher in the severe AKI group than in the opposite group. The AuROC showed that both NAG and alpha 1M values at day 7 had moderate discriminative sensitivity for predicting severe AKI (NAG : 0.783, 95 % confidence interval [CI] 0.611-0.966 ; and alpha 1M: 0.807, 95 % CI 0.647-0.956, respectively). Multivariate logistic regression showed that only alpha 1M at day 7 was significantly associated with the occurrence of severe AKI(odds ratio 18.4, 95 % CI 1.210-736, p=0.035).Consecutive monitoring of urinary alpha 1M after SCT is likely to be useful for early identification of patients at risk for severe AKI, leading to early death.