title: The impact of oxidized serum albumin on the oncotic pressure and hydration status of peritoneal dialysis patients.
abstract: OBJECTIVE
  Hypoalbuminemia, fluid overload (FO), and oxidative stress (OS) may be related to cardiovascular morbidity and mortality in peritoneal dialysis (PD) patients. OS produces molecular modifications of serum albumin that interfere with its quantification by the commonly used bromocresol green assay. This study evaluated the impact of oxidized serum albumin (OSA) on oncotic pressure (OP) and hydration status.
  
  
  METHODS
  Twenty-four stable hypoalbuminemic PD patients were enrolled in the study. After performing physical examination, assessment of the hydration status using a whole-body bioimpedance spectroscopy technique was performed, and blood samples were drawn for determination of OP, serum albumin levels, and OSA.
  
  
  RESULTS
  Extracellular to total body water (E/TBW) ratio was higher in patients with FO ≥1.5 L with or without edema than in patients with FO <1.5 L (P≤0.043). E/TBW ratio was higher in patients with FO ≥1.5 L and edema compared to those with FO ≥1.5 L but without edema (P=0.004). OP was significantly higher in patients with FO ≥1.5 L and without edema compared to those with FO ≥1.5 L and with edema (P<0.001). Albumin-detection index (ADI) in patients with FO ≥1.5 L and without edema was similar to ADI in patients with FO <1.5 L (P=0.520). ADI was significantly lower in patients with FO ≥1.5 L and without edema compared to those with FO ≥1.5 L and edema (P=0.034). E/TBW ratio correlated positively with the ADI (r=0.60, P=0.001) and inversely with the OP (r=-0.54, P=0.002).
  
  
  CONCLUSIONS
  Overhydration may be clinically undetectable in PD patients. Assessing the hydration status and measuring the total serum albumin levels, including the oxidized fraction, should be considered in evaluating hydration status in PD patients.
authors.affiliation: Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel; Peritoneal Dialysis Unit, Department of Nephrology and Hypertension, Galilee Medical Center, Nahariya, Israel.
authors.forename: Kamal
authors.initials: K
authors.lastname: Hassan
authors.affiliation: Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel; Peritoneal Dialysis Unit, Department of Nephrology and Hypertension, Galilee Medical Center, Nahariya, Israel.
authors.forename: Batya
authors.initials: B
authors.lastname: Kristal
authors.affiliation: Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Fadi
authors.initials: F
authors.lastname: Hassan
authors.affiliation: Department of Urology, Galilee Medical Center, Nahariya, Israel.
authors.forename: Saad
authors.initials: S
authors.lastname: Abo Saleh
authors.affiliation: Eliachar Research Laboratory, Galilee Medical Center, Nahariya, Israel.
authors.forename: Regina
authors.initials: R
authors.lastname: Michelis
keywords: hydration status; oncotic pressure; oxidized serum albumin; peritoneal dialysis