title: Effects of Serum Uric Acid on Estimated GFR in Cardiac Surgery Patients: A Pilot Study.
abstract: BACKGROUND
  The aim of the study was to investigate the effects of serum uric acid (SUA) on acute kidney injury (AKI) in patients undergoing cardiac surgery.
  
  
  METHODS
  Prospectively collected data from a previous study were analyzed to investigate the relationship between SUA and AKI as assessed by neutrophil gelatinase-associated lipocalin (NGAL), serum creatinine (SCr) and kinetic estimated glomerular filtration rate (KeGFR).
  
  
  RESULTS
  Patients undergoing cardiovascular surgery (n = 37) were included. SUA was measured at postoperative 1 h. Statistically significant correlations were present between SUA and NGAL measured at postoperative 1 h (r = 0.39, p = 0.008), 6 h (r = 0.31, p = 0.029) and 24 h (r = 0.31, p < 0.001), respectively. Significant correlations were also noted between SUA and SCr measured on postoperative day 1 (r = 0.41, p = 0.006), day 2 (r = 0.29, p = 0.042) and day 3 (r = 0.42, p = 0.009). Negative correlations were demonstrated between SUA and day 1 (r = -0.44, p = 0.007), day 2 (r = -0.43, p = 0.007), day 3 (r = -0.44, p = 0.006 and day 4 KeGFR (r = -0.35, p = 0.035). The inverse relationship of SUA and KeGFR was also demonstrated with a different method (Jelliffe) of measurement.
  
  
  CONCLUSIONS
  A reduction in glomerular filtration rate (GFR) can lead to a rise in SUA. However, in this study, we are able to show that SUA at 1 h (maximal dilution time) effectively predicts subsequent changes in urinary NGAL, SCr, KeGFR, and the development of AKI. Thus, these findings suggest that uric acid precedes and predicts acute changes in renal function and cannot be ascribed to a simple relationship in which a reduced GFR raises SUA.
authors.affiliation: Division of Nephrology, Hypertension and Transplantation, University of Florida, Gainesville, Fla., USA.
authors.forename: A Ahsan
authors.initials: AA
authors.lastname: Ejaz
authors.forename: Kawther F
authors.initials: KF
authors.lastname: Alquadan
authors.forename: Bhagwan
authors.initials: B
authors.lastname: Dass
authors.forename: Michiko
authors.initials: M
authors.lastname: Shimada
authors.forename: Mehmet
authors.initials: M
authors.lastname: Kanbay
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Johnson
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood*; D000209:Acute-Phase Proteins; D000368:Aged; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures; D016022:Case-Control Studies; D003324:Coronary Artery Disease / Q000601:surgery; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D000071068:Lipocalin-2; D054834:Lipocalins / Q000097:blood; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000627:therapeutic use; D010865:Pilot Projects; D011184:Postoperative Period; D011446:Prospective Studies; D011518:Proto-Oncogene Proteins / Q000097:blood; D013997:Time Factors; D014527:Uric Acid / Q000097:blood* / Q000378:metabolism
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D020097:Natriuretic Peptide, Brain; D014527:Uric Acid; D003404:Creatinine