title: Brain Natriuretic Peptide and Body Fluid Composition in Patients with Chronic Kidney Disease: A Cross-Sectional Study to Evaluate the Relationship between Volume Overload and Malnutrition.
abstract: OBJECTIVE
  Fluid volume overload occurs in chronic kidney disease (CKD), leading to the compensatory release of natriuretic peptides. However, the elevated cardiac peptides may also be associated with malnutrition as well as volume overload.
  
  
  METHODS
  Body fluid composition was measured in 147 patients with CKD between 2009 and 2015, and its relationship to brain natriuretic peptide (BNP) levels was examined. Body fluid composition was separated into three components: (a) a water-free mass consisting of muscle, fat, and minerals; (b) intracellular water (ICW) content, and (c) extracellular water (ECW) content. Excess fluid mass was calculated using Chamney's formula.
  
  
  RESULTS
  The measured BNP levels in the tertile groups were 10.9 ± 5.4, 36.3 ± 12.5, and 393 ± 542 pg/ml, respectively. Patients in a higher log-transformed BNP level tertile were more likely to be older, to have a higher frequency of cardiac comorbidities, pulse pressure, C-reactive protein levels, and proteinuria, and to have lower serum sodium, kidney function, and serum albumin (p < 0.05). In body fluid composition, decreased body mass was significantly associated with the ECW-to-ICW ratio in relation to the downward ICW slope (r = -0.235, p = 0.004) and was strongly correlated with excess fluid mass (r = -0.701, p < 0.001). The ECW-to-ICW ratio and excess fluid mass was independently associated with the BNP levels.
  
  
  CONCLUSIONS
  Fluid volume imbalance between intra- and extracellular water regulated by decreased cell mass was independently associated with BNP levels, which may explain the reserve capacity for fluid accumulation in patients with CKD.
authors.affiliation: Department of Nephrology, Sakura Medical Center, School of Medicine, Toho University, Chiba, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ohashi
authors.affiliation: Department of Nephrology, Omori Medical Center, School of Medicine, Toho University, Tokyo, Japan.
authors.forename: Akinobu
authors.initials: A
authors.lastname: Saito
authors.affiliation: Department of Nephrology, Sakura Medical Center, School of Medicine, Toho University, Chiba, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yamazaki
authors.affiliation: Department of Nephrology, Omori Medical Center, School of Medicine, Toho University, Tokyo, Japan.
authors.forename: Reibin
authors.initials: R
authors.lastname: Tai
authors.affiliation: Department of Nephrology, Omori Medical Center, School of Medicine, Toho University, Tokyo, Japan.
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Matsukiyo
authors.affiliation: Department of Nephrology, Omori Medical Center, School of Medicine, Toho University, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Aikawa
authors.affiliation: Department of Nephrology, Omori Medical Center, School of Medicine, Toho University, Tokyo, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Sakai
keywords: Bioimpedance analysis; Brain natriuretic peptide; Chronic kidney disease; Fluid overload; Malnutrition