Changes in renal function are one of the most common manifestations of severe illness. There is a clinical need to intervene early with proven treatments in patients with potentially deleterious changes in renal function. Unfortunately progress has been hindered by poor definitions of renal dysfunction and a lack of early biomarkers of renal injury. In recent years, the definitional problem has been addressed with the establishment of a new well-defined diagnostic entity, acute kidney injury (AKI), which encompasses the wide spectrum of kidney dysfunction, together with clearer definition and sub-classification of the cardio-renal syndromes. From the laboratory have emerged new biomarkers which allow early detection of AKI, including neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C. This review describes the new concepts of AKI and the cardio-renal syndromes as well as novel biomarkers which allow early detection of AKI. Panels of AKI biomarker tests are likely to revolutionise the diagnosis and management of critically ill patients in the coming years. Earlier diagnosis and intervention should significantly reduce the morbidity and mortality associated with acute kidney damage.
Acute Kidney Injury/*diagnosis ; Biological Markers/analysis/blood/urine ; Cystatin C/blood/urine ; Heart Failure/complications/etiology ; Humans ; Kidney Diseases/complications/*diagnosis/etiology ; Lipocalins/blood/urine ; Syndrome

BACKGROUNDAcute renal failure (ARF) after liver transplantation is associated with high mortality and morbidity. Early therapeutic or preventive intervention is hampered by the lack of early effective prognostic factors. Recent studies indicated that serum levels of cystatin C and beta2-microglobulin (beta2 MG) as well as urinary beta2 MG and N-acetyl-beta-D-glucosaminidase (NAG) would increase in patients with early and mild renal impairment. In this study, these factors were detected during the different stages in patients who accepted orthotopic liver transplantation (OLT), and their feasibilities to predict early ARF after OLT were also analyzed.

METHODSSixty patients with normal blood urea nitrogen (BUN) and serum creatinine (SCr) who received modified piggyback liver transplantation without veno-venous bypass were prospectively studied. Blood samples were drawn from patients for the determination of serum beta2 MG (n = 60), SCr (n = 60) and serum Cystatin C (n = 39) at following 5 intervals: before operation (T0), 20 minutes before anhepatic phase (T1), 25 minutes in anhepatic (T2), 60 minutes after reperfusion (T3) and at the end of operation (T4). Urinary beta2 MG (n = 60) and NAG (n = 60) were also examined at following 3 intervals: before operation (T0), 60 minutes after reperfusion (T3) and at the end of operation (T4). According to the Rimola A criteria of ARF in 24 hours after operation, all the patients were divided into two groups: ARF group and non-ARF group. The data were statistically analyzed to evaluate the feasibiliy of regarding these factors as prognostic factors for early ARF after liver transplantation in patients with normal SCr and BUN before operation.

RESULTSTen of sixty cases showed ARF (16.7%). The Logistic regression analysis showed that the levels of serum and urinary beta2 MG as well as serum cystatin C before operation were correlated with early ARF after liver transplantation (P < 0.05), while only serum levels of cystatin C and Cr at the end of operation correlated with early ARF (P < 0.05, P < 0.01) after liver transplantation. The serum beta2 MG, Cystatin C, SCr and urinary beta2 MG levels in ARF group were much more higher than that in non-ARF group (P < 0.05, P < 0.01). There were significant differences between the correct and false predictive positive ratios of serum cystatin C, serum and urinary beta2 MG levels before operation (P < 0.05, P < 0.01), while only SCr showed significant difference between these groups at the end of operation (P < 0.01).

CONCLUSIONSThe results revealed that there was potential renal damage among those patients who demonstrated normal SCr and BUN before operation, and that liver transplantation could aggravate this damage and causing ARF. Here we provided the prognostic values of serum Cystatin C, beta2 MG, urinary beta2 MG and NAG in patients with early acute renal failure after liver transplantation.

Acetylglucosaminidase ; urine ; Acute Kidney Injury ; blood ; diagnosis ; urine ; Adult ; Blood Urea Nitrogen ; Cystatin C ; blood ; Female ; Humans ; Liver Transplantation ; adverse effects ; Male ; Middle Aged ; Postoperative Complications ; blood ; diagnosis ; urine ; Predictive Value of Tests ; Prognosis ; beta 2-Microglobulin ; analysis ; blood ; urine

Spot urinary albumin to creatinine ratio (ACR) measurement has been suggested as a surrogate to 24-hr urine collection for the assessment of microalbuminuria, and cystatin C (cysC) is known as an advantageous marker for renal function. The aim of this study was to evaluate the clinical values of spot urinary ACR and serum cysC for the assessment of diabetic nephropathy instead of 24-hr urine microalbumin in children and adolescents with diabetes. A total of 113 children and adolescents (age 12-19 yr, M:F = 47:66) with type 1 or 2 diabetes were enrolled. We evaluated the validity of spot urine ACR and serum cysC, and then compared them to 24-hr urine microalbumin and creatinine clearance. Spot urine ACR was correlated with 24-hr urine albumin excretion (R2 = 0.828, P = 0.001) and creatinine clearance (R2 = 0.249, P = 0.017). The ROC curve analysis of serum cysC demonstrated higher diagnostic accuracy than that of serum creatinine (AUC 0.732 vs 0.615). Both the measurements of spot urine ACR and serum cysC might better predict the presence of diabetic nephropathy than 24-hr urine microalbumin in childhood diabetic patients.
Adolescent ; Albuminuria/*urine ; Child ; Creatinine/*urine ; Cystatin C/*blood ; Diabetes Mellitus, Type 1/*diagnosis ; Diabetes Mellitus, Type 2/*diagnosis ; Diabetic Nephropathies/*diagnosis ; Female ; Glomerular Filtration Rate ; Hemoglobin A, Glycosylated/analysis ; Humans ; Kidney Function Tests ; Male ; Predictive Value of Tests ; ROC Curve

BACKGROUND/AIMS: The present study aimed to determine the role of cystatin C as a prognostic factor for acute kidney injury and survival in cirrhotic patients. METHODS: The study investigated 53 liver cirrhosis patients. The renal function was evaluated by serum creatinine, serum and urine cystatin C, and 24-hour creatinine clearance on admission. Acute kidney injury was defined as a serum creatinine level exceeding the normal range (>1.2 mg/dl) and an increase of at least 50% from the baseline value. Multivariate analysis, receiver operating characteristic curve, and survival analysis were used to investigate prognostic factors for acute kidney injury and survival. RESULTS: Nine of the 53 cirrhotic patients (17.0%) developed acute kidney injury within 3 months. Both serum creatinine and cystatin C were predictive factors for acute kidney injury in univariate analysis, with a diagnostic accuracy of 0.735 (95% confidence interval (CI), 0.525-0.945; p=0.028) for serum cystatin C and 0.698 (95% CI, 0.495-0.901, p=0.063) for creatinine. In multivariate analysis, only serum cystatin C was an independent risk factor for acute kidney injury. The sensitivity and specificity of a serum cystatin C level of >1.23 mg/L to acute kidney injury were 66% and 86%, respectively. Serum cystatin C was positively correlated with the Model for End-Stage Liver Disease (MELD) and MELD-Na scores (r=0.346 and p=0.011, and r=0.427 and p=0.001, respectively). Comparison of the survival rates over the observation period revealed that a serum cystatin C level of >1.23 mg/L was a useful marker for short-term mortality (p<0.001). CONCLUSIONS: The accuracy in predicting acute kidney injury and short-term mortality was higher for a serum cystatin C level of >1.23 mg/L than for the serum creatinine concentration in patients with cirrhosis.
Acute Kidney Injury/complications/*diagnosis/mortality ; Adult ; Aged ; Creatinine/blood ; Cystatin C/*analysis/blood/urine ; Female ; Humans ; Liver Cirrhosis/blood/*complications ; Male ; Middle Aged ; Multivariate Analysis ; Predictive Value of Tests ; ROC Curve ; Risk Factors ; Severity of Illness Index ; Survival Rate