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Introduction: It has been demonstrated that urinary neutrophil gelatinase-associated lipocalin (NGAL) and calprotectin are helpful biomarkers in the differentiation of intrinsic and prerenal acute kidney injury., Objective: The present cross-sectional study investigates, whether urinary biomarkers are able to differentiate primarily inflammatory from non-inflammatory entities in chronic kidney disease (CKD)., Methods: Urinary calprotectin, NGAL, and kidney injury molecule-1 (KIM-1) concentrations were assessed in a study population of 143 patients with stable CKD and 29 healthy controls. Stable renal function was defined as an eGFR fluctuation ≤5 ml/min/1.73 m 2 in the past 12 months. Pyuria, metastatic carcinoma, and renal transplantation were regarded as exclusion criteria. Diabetic nephropathy, hypertensive nephropathy, and polycystic kidney disease were categorized as 'primarily non-inflammatory renal diseases' (NIRD), whereas glomerulonephritis and vasculitis were regarded as 'primarily inflammatory renal diseases' (IRD)., Results: Urinary calprotectin and NGAL concentrations significantly differed between CKD and healthy controls ( p  < 0.05 each), whereas KIM-1 concentrations did not ( p  = 0.84). The three biomarkers did neither show significant differences in-between the individual entities, nor the two categories of IRD vs. NIRD (calprotectin 155.7 vs. 96.99 ng/ml; NGAL 14 896 vs. 11 977 pg/ml; KIM-1 1388 vs. 1009 pg/ml; p  > 0.05 each). Albumin exceeds the diagnostic power of the investigated biomarkers by far., Conclusions: The urinary biomarkers calprotectin, NGAL, and KIM-1 have no diagnostic value in the differentiation of primarily inflammatory vs. non-inflammatory etiologies of CKD.

Objective: This study aimed to determine the biomarker-specific outcome patterns and short-and long-term prognosis of cardiac surgery-asoociated acute kidney injury (AKI) identified by standard criteria and/or urinary kidney biomarkers., Methods: Patients enrolled (N = 200), originated a German multicenter study (NCT00672334). Standard risk injury, failure, loss, and end-stage renal disease classification (RIFLE) criteria (including serum creatinine and urine output) and urinary kidney biomarker test result (neutrophil gelatinase-associated lipocalin, midkine, interleukin 6, and proteinuria) were used for diagnosis of postoperative AKI. Primary end point was acute renal replacement therapy or in-hospital mortality. Long-term end points among others included 5-year mortality. Patients with single-biomarker-positive subclinical AKI (RIFLE negative) were identified. We controlled for systemic inflammation using C-reactive protein test., Results: Urinary biomarkers (neutrophil gelatinase-associated lipocalin, midkine, and interleukin 6) were identified as independent predictors of the primary end point. Neutrophil gelatinase-associated lipocalin, midkine, or interleukin 6 positivity or de novo/worsening proteinuria identified 21.1%, 16.9%, 30.5%, and 48.0% more cases, respectively, with likely subclinical AKI (biomarker positive/RIFLE negative) additionally to cases with RIFLE positivity alone. Patients with likely subclinical AKI (neutrophil gelatinase-associated lipocalin or interleukin 6 positive) had increased risk of primary end point (adjusted hazard ratio, 7.18; 95% confidence interval, 1.52-33.93 [P = .013] and hazard ratio, 6.27; 95% confidence interval, 1.12-35.21 [P = .037]), respectively. Compared with biomarker-negative/RIFLE-positive patients, neutrophil gelatinase-associated lipocalin positive/RIFLE-positive or midkine-positive/RIFLE-positive patients had increased risk of primary end point (odds ratio, 9.6; 95% confidence interval, 1.4-67.3 [P = .033] and odds ratio, 14.7; 95% confidence interval, 2.0-109.2 [P = .011], respectively). Three percent to 11% of patients appear to be influenced by single-biomarker-positive subclinical AKI. During follow-up, kidney biomarker-defined short-term outcomes appeared to translate into long-term outcomes., Conclusions: Urinary kidney biomarkers identified RIFLE-negative patients with high-risk subclinical AKI as well as a higher risk subgroup of patients among RIFLE-AKI-positive patients. These findings support the concept that urinary biomarkers define subclinical AKI and higher risk subpopulations with worse long-term prognosis among standard patients with AKI., (Copyright © 2017 The American Association for Thoracic Surgery. All rights reserved.)