title: Serum uric acid, protein intake and mortality in hemodialysis patients.
abstract: BACKGROUND
  The association between serum uric acid (SUA) and mortality has been conflicting among studies using hemodialysis (HD) patients. Given the close link between purine and protein in foods, we hypothesized that normalized protein catabolic rate (nPCR), a dietary protein intake surrogate, modifies the SUA-mortality association in the HD population.
  
  
  METHODS
  We identified 4298 patients who initiated HD and had one or more SUA measurement in a contemporary cohort of HD patients over 5 years (1 January 2007-31 December 2011), and examined survival probability according to the first uric acid measurement, adjusting for dialysis vintage, case-mix and malnutrition-inflammation complex-related variables.
  
  
  RESULTS
  Mean SUA concentration was 6.6 ± 1.8 mg/dL. There was a consistent association of higher SUA with better nutritional status and lower all-cause mortality irrespective of adjusted models (Ptrend < 0.001). In the case-mix adjusted model, the highest SUA category (≥8.0 mg/dL) compared with the reference group (>6.0-7.0 mg/dL) showed no significant mortality risk [hazard ratio (HR) 0.90, 95% confidence interval (CI) 0.72-1.13], while the lowest category (<5.0 mg/dL) was associated with higher mortality (HR 1.42, 95% CI 1.16-1.72). The hypouricemia-mortality association was significantly modified by nPCR (Pinteraction = 0.001). Mortality risk of low SUA (<5.0 mg/dL) persisted among patients with low nPCR (<0.9 g/kg/day; HR 1.73, 95% CI 1.42-2.10) but not with high nPCR (≥0.9 g/kg/day; HR 0.99, 95% CI 0.74-1.33).
  
  
  CONCLUSIONS
  SUA may be a nutritional marker in HD patients. Contrary to the general population, low but not high SUA is associated with higher all-cause mortality in HD patients, especially in those with low protein intake. Nutritional features of SUA warrant additional studies.
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Park
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Obi
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Elani
authors.initials: E
authors.lastname: Streja
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Connie M
authors.initials: CM
authors.lastname: Rhee
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Christina J
authors.initials: CJ
authors.lastname: Catabay
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Nosratola D
authors.initials: ND
authors.lastname: Vaziri
authors.affiliation: Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA.|Nephrology Section, Memphis VA Medical Center, Memphis, TN, USA.
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA.|Fielding School of Public Health at UCLA, Los Angeles, CA.|Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, CA, USA.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D015331:Cohort Studies; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D006435:Renal Dialysis / Q000401:mortality*; D012307:Risk Factors; D015996:Survival Rate; D014527:Uric Acid / Q000097:blood*
chemical_list: D015415:Biomarkers; D004044:Dietary Proteins; D014527:Uric Acid
keywords: chronic hemodialysis; hyperuricemia; nutrition; survival analysis; uric acid