***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : Acute renal dysfunction ( ARD ) and subsequent acute renal failure after cardiac surgery are associated with high mortality and morbidity . Early therapeutic or preventive intervention is hampered by the lack of an early biomarker for acute renal injury . Recent studies showed that urinary neutrophil gelatinase – associated lipocalin ( NGAL or lipocalin 2 ) is up-regulated early ( within 1–3 h ) after murine renal injury and in pediatric ARD after cardiac surgery . The authors hypothesized that postoperative urinary NGAL concentrations are increased in adult patients developing ARD after cardiac surgery compared with patients without ARD . Methods : After institutional review board approval , 81 cardiac surgical patients were prospect ively studied .  Urine sample s were collected immediately before incision and at various time intervals after surgery for NGAL analysis by quantitative immunoblotting . ARD was defined as peak postoperative serum creatinine increase by 50 % or greater compared with preoperative serum creatinine . Results : Sixteen of 81 patients ( 20 % ) developed postoperative ARD , and the mean urinary NGAL concentrations in patients who developed ARD were significantly higher early after surgery ( after 1 h : 4,195 ± 6,520 [ mean ± SD ] vs. 1,068 ± 2,129 ng/ml ; P < 0.01 ) compared with patients who did not develop ARD . Mean urinary NGAL concentrations continued to increase and remained significantly higher at 3 and 18 h after cardiac surgery in patients with ARD . In contrast , urinary NGAL in patients without ARD decreased rapidly after cardiac surgery . Conclusions : Patients developing postoperative ARD had significantly higher urinary NGAL concentrations early after cardiac surgery . Urinary NGAL may therefore be a useful early biomarker of ARD after cardiac surgery . These findings may facilitate the early detection of acute renal injury and potentially prevent progression to acute renal failure BACKGROUND AND OBJECTIVES The authors have previously shown that urine neutrophil gelatinase-associated lipocalin ( NGAL ) , measured by a research ELISA , is an early predictive biomarker of acute kidney injury ( AKI ) after cardiopulmonary bypass ( CPB ) . In this study , whether an NGAL immunoassay developed for a st and ardized clinical platform ( ARCHITECT analyzer , Abbott Diagnostics Division , Abbott Laboratories , Abbott Park , IL ) can predict AKI after CPB was tested . DESIGN , SETTING , PARTICIPANTS , & MEASUREMENTS In a pilot study with 136 urine sample s ( NGAL range , 0.3 to 815 ng/ml ) and 6 calibration st and ards ( NGAL range , 0 to 1000 ng/ml ) , NGAL measurements by research ELISA and by the ARCHITECT assay were highly correlated ( r = 0.99 ) . In a subsequent study , 196 children undergoing CPB were prospect ively enrolled and serial urine NGAL measurements obtained by ARCHITECT assay . The primary outcome was AKI , defined as a > or = 50 % increase in serum creatinine . RESULTS AKI developed in 99 patients ( 51 % ) , but the diagnosis using serum creatinine was delayed by 2 to 3 d after CPB . In contrast , mean urine NGAL levels increased 15-fold within 2 h and by 25-fold at 4 and 6 h after CPB . For the 2-h urine NGAL measurement , the area under the curve was 0.95 , sensitivity was 0.82 , and the specificity was 0.90 for prediction of AKI using a cutoff value of 100 ng/ml . The 2-h urine NGAL levels correlated with severity and duration of AKI , length of stay , dialysis requirement , and death . CONCLUSIONS Accurate measurements of urine NGAL are obtained using the ARCHITECT platform . Urine NGAL is an early predictive biomarker of AKI severity after CPB Objective : To compare the value of novel with conventional serum biomarkers in the prediction of  acute kidney injury ( AKI ) in adult cardiac surgical patients according to preoperative renal function . Design : Single-center , prospect i ve observational study . Setting : Tertiary hospital . Patients : One hundred adult cardiac surgical patients . Measurements and Main Results : We measured  concentrations of plasma neutrophil gelatinase-associated lipocalin ( NGAL ) , and serum cystatin C , and creatinine and urea at baseline , on arrival in the intensive care unit ( ICU ) and at 24 hours postoperatively . We assessed such biomarkers in relation to the development of AKI ( > 50 % increase in creatinine from baseline ) and to a composite end point ( need for renal replacement therapy and in-hospital mortality ) . We defined an area under the receiver operating characteristic curve of 0.60–0.69 as poor , 0.70–0.79 as fair , 0.80–0.89 as good , and 0.90–1.00 as excellent in terms of predictive value . On arrival in ICU , plasma NGAL and serum cystatin C were of good predictive value , but creatinine and urea were of poor predictive value . After exclusion of patients with preoperative renal impairment ( estimated glomerular filtration rate < 60 mL/min ) , the predictive performance for AKI of all renal biomarkers on arrival in ICU remained unchanged except for cystatin C , which was of fair value in such patients . At 24 hours postoperatively , all renal biomarkers were of good predictive value . On arrival in ICU , novel biomarkers were superior to conventional biomarkers ( p < 0.05 ) . Plasma NGAL ( p = 0.015 ) and serum cystatin C ( p = 0.007 ) were independent predictors of AKI and of excellent value in the prediction of the composite end point . Conclusions : Early postoperative measurement of plasma NGAL was of good value in identifying patients who developed AKI after adult cardiac surgery .  Plasma NGAL and serum cystatin C were superior to conventional biomarkers in the prediction of AKI and were also of prognostic value in this setting Neutrophil gelatinase‐associated lipocalin ( NGAL ) is a measure of acute kidney injury . Renal dysfunction portends significant risk after discharge from acute heart failure ( AHF ) . Thus , a sensitive marker of renal injury might also help to risk stratify HF patients OBJECTIVES The aim of this study was to test the hypothesis that , without diagnostic changes in serum creatinine , increased neutrophil gelatinase-associated lipocalin ( NGAL ) levels identify patients with sub clinical acute kidney injury ( AKI ) and therefore worse prognosis . BACKGROUND Neutrophil gelatinase-associated lipocalin detects sub clinical AKI hours to days before increases in serum creatinine indicate manifest loss of renal function . METHODS We analyzed pooled data from 2,322 critically ill patients with predominantly cardiorenal syndrome from 10 prospect i ve observational studies of NGAL .  We used the terms NGAL(- ) or NGAL(+ ) according to study -specific NGAL cutoff for optimal AKI prediction and the terms sCREA(- ) or sCREA(+ ) according to consensus diagnostic increases in serum creatinine defining AKI . A priori-defined outcomes included need for renal replacement therapy ( primary endpoint ) , hospital mortality , their combination , and duration of stay in intensive care and in-hospital . RESULTS Of study patients , 1,296 ( 55.8 % ) were NGAL(-)/sCREA(- ) , 445 ( 19.2 % ) were NGAL(+)/sCREA(- ) , 107 ( 4.6 % ) were NGAL(-)/sCREA(+ ) , and 474 ( 20.4 % ) were NGAL(+)/sCREA(+ ) . According to the 4 study groups , there was a stepwise increase in subsequent renal replacement therapy initiation-NGAL(-)/sCREA(- ) : 0.0015 % versus NGAL(+)/sCREA(- ) : 2.5 % ( odds ratio : 16.4 , 95 % confidence interval : 3.6 to 76.9 , p < 0.001 ) , NGAL(-)/sCREA(+ ) : 7.5 % , and NGAL(+)/sCREA(+ ) : 8.0 % , respectively , hospital mortality ( 4.8 % , 12.4 % , 8.4 % , 14.7 % , respectively ) and their combination ( 4-group comparisons : all p < 0.001 ) . There was a similar and consistent progressive increase in median number of intensive care and in-hospital days with increasing biomarker positivity : NGAL(-)/sCREA(- ) : 4.2 and 8.8 days ; NGAL(+)/sCREA(- ) : 7.1 and 17.0 days ; NGAL(-)/sCREA(+ ) : 6.5 and 17.8 days ; NGAL(+)/sCREA(+ ) : 9.0 and 21.9 days ; 4-group comparisons : p = 0.003 and p = 0.040 , respectively . Urine and plasma NGAL indicated a similar outcome pattern . CONCLUSIONS In the absence of diagnostic increases in serum creatinine , NGAL detects patients with likely sub clinical AKI who have an increased risk of adverse outcomes . The concept and definition of AKI might need re- assessment We hypothesized that use of Schwartz formula underestimates the prevalence of CKD in PHT recipients . This study determined the prevalence and risk factors for CKD in PHT using novel methods -serum cystatin C , CKiD formula , Revised Schwartz formula , s- and u-NGAL . Serum BUN , creatinine , cystatin C and s- and u-NGAL  were measured after prospect i ve enrollment . Schwartz formula GFR was compared with novel methods . CKD was defined as CKiD GFR < 90 mL/min/1.73 m(2 ) . The s- and  u-NGAL  were compared between those with and without CKD . Potential risk factors for CKD were analyzed . Seventy-nine patients ( 46 male children or boys ) , mean age 9.9 ± 5.8 yr formed the study cohort .  The prevalence of mild and moderate CKD was 2- to 3-fold higher using novel methods compared to Schwartz formula . u-NGAL and u-NGAL/Cr were significantly higher in patients with CKD . u- and s-NGAL had negative correlation with estimates of GFR . Women were at a higher risk for CKD ( odds ratio 8.7 ) as was longer duration since transplant ( p = 0.009 ) . In conclusion , use of novel methods of GFR estimation unmasked 2- to 3-fold increased prevalence of CKD in PHT . Women and those with longer duration since transplant are at higher risk for CKD In very low birth weight ( VLBW ) infants , acute renal impairment ( ARI ) is common , but there is no consensus about criteria for its diagnosis . Neutrophil gelatinase-associated lipocalin ( NGAL ) is an early and sensitive indicator of renal impairment in experimental animals , children , and adults . Urinary NGAL ( UNGAL ) is detectable in VLBW infants ; however , there is no reference range in this population . The objective of this study is to define the reference range for UNGAL in VLBW infants with no risk factors for acute renal impairment .  UNGAL concentration was determined in urine sample s collected from day of life ( DOL ) 4 through DOL 30 in 50 newborns with uncomplicated clinical courses , selected from a total of 145 prospect ively enrolled appropriate for gestational age inborn VLBW premature infants . The birth weight and gestational age ranges were 790 - 1490 g and 26–33 wk , respectively . The median , 95th and 99th percentiles , and range of pooled UNGAL values were 5 ng/mL , 50 ng/mL , 120 ng/mL , and 2–150 ng/mL , respectively . Greater variability and higher quantile levels of UNGAL were observed in females versus males . In conclusion , a reference range for UNGAL in VLBW infants , similar to that in children and adults , has been established Background / Aims : Contrast-induced nephropathy ( CIN ) is at present the third leading cause of hospital-acquired acute kidney injury ( AKI ) . Traditionally , it is diagnosed by measuring the increase of the serum creatinine concentration . However , in patients with acute changes in their glomerular filtration rate , serum creatinine is an insensitive marker . This clinical study was design ed to investigate whether human urinary interleukin-18 ( IL-18 ) and neutrophil gelatinase-associated lipocalin ( NGAL ) are early predictive markers for AKI after coronary angiography and their correlation with later cardiac events . Methods : Patients undergoing coronary angiography using low-osmolar contrast medium were enrolled and then followed up for at least 17 months . Urine sample s were collected before and 24 h after coronary angiography and  IL-18 and NGAL levels measured by using an ELISA kit . Results : CIN was diagnosed in 13 of 150 ( 8.7 % ) patients ( CIN group ) ; 27 patients 
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However , it is important to note that NGAL , in the absence of diagnostic increases in serum creatinine , is able to detect some patients affected by sub clinical AKI who have an increased risk of adverse outcomes .