title: Prognostic significance of NGAL in early stage chronic kidney disease.
abstract: BACKGROUND
  Neutrophilgelatinase-associated lipocalin (NGAL) has been proven to be a useful biomarker for early detection of acute kidney injury, but it is not known whether adding NGAL measurements to conventional risk factors will improve the risk assessment in the setting of chronic kidney disease (CKD). The aim of the present study was to examine the correlation of NGAL with early stage renal impairment in CKD and to evaluate its prognostic value in these subjects.
  
  
  METHODS
  This is a prospective observational cohort study of 54 patients with early stage (stage 1-2) CKD. Patients aged between 18 and 65 years with stable disease were enrolled in this study. Patients with a history of primary glomerulonephritis, diabetes mellitus, acute kidney injury, systemic diseases and stage 3-4-5 CKD were excluded from the study group. Estimated glomerular filtration (eGFR) rate was calculated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. The patients were followed for two years to determine the ability of baseline NGAL for prediction of renal outcome. In our study disease progression was defined as changes in eGFR (ΔeGFR) and proteinuria (Δproteinuria). Patients divided into two groups according to NGAL cut-off value as group 1 (N.=23, NGAL ≤98.71 ng/mL) and group 2 (N.=31, NGAL >98.71 ng/mL).
  
  
  RESULTS
  Out of 54 patients (mean age: 45.6±7.6 years, 64.8% female, baseline eGFR: 84.6±16.8 mL/min/1.73 m2, baseline NGAL level: 157.47±121.52 ng/mL); 18 patients were stage 1 and 36 patients were stage 2 CKD. In the ROC analysis, we found that the optimal cut-off value of NGAL for predicting stage 2 CKD was 98.71ng/mL (P=0.005) with the 72.2% sensitivity and 72.2% specificity. In correlation analysis, we evaluated significantly positive correlations between NGAL and CKD stage (r=0.389, P=0.004), baseline/last serum creatinine level (r=0.530, P<0.001 and r=0.439, P=0.003; respectively), last proteinuria level (r=0.359, P=0.043). There were significantly negative correlation between NGAL and baseline/last eGFR (r=-0.498, P<0.001 and r=-0.462, P=0.002; respectively). Compared to the group 1, we determined that group 2 patients had further deterioration in renal functions regarding ΔeGFR (-1.12±12.6 mL/min vs. -1.46±12.4 mL/min: respectively, P=0.930) and Δproteinuria (98.1±569.3 mg/day vs. 339±701.6 mg/day; respectively, P=0.305); however these differences were not statistically significant at the end of the two years follow-up period.
  
  
  CONCLUSIONS
  Altough NGAL has a positive correlation with disease severity, it does not seem to be a marker of disease progression in patients with early stage CKD. But further studies stated in different patient groups may also explain the usability of NGAL in clinical practice.
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey - tanerbast@yahoo.com.
authors: Taner
authors: T
authors: Basturk
authors: Department of Biochemistry, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Ozlem
authors: O
authors: Sari
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Yener
authors: Y
authors: Koc
authors: Department of Biochemistry, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Nezaket
authors: N
authors: Eren
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Mahmoud
authors: M
authors: Isleem
authors: Division of Nephrology, Department of Internal Medicine, Medical Faculty, Recep Tayyip Erdogan University, Rize, Turkey.
authors: Ekrem
authors: E
authors: Kara
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Mustafa
authors: M
authors: Sevinc
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Tamer
authors: T
authors: Sakaci
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Elbis
authors: E
authors: Ahbap
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Nuri B
authors: NB
authors: Hasbal
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Feyza
authors: F
authors: Bayrakdar Caglayan
authors: Department of Nephrology, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors: Abdulkadir
authors: A
authors: Unsal
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D000071068:Lipocalin-2 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000503:physiopathology
chemical_list: D015415:Biomarkers; C489506:LCN2 protein, human; D000071068:Lipocalin-2