title: Hypervolemia induced by fluid ingestion at rest: effect of sodium concentration.
abstract: OBJECTIVE
  Sodium drink is used as a countermeasure against body fluid loss. However, high concentrations of sodium may cause gastrointestinal upset (e.g., diarrhea). We sought to determine the sodium concentration that induces hypervolemia with a minimal risk of gastrointestinal disturbance.
  
  
  METHODS
  Eight healthy active males rested in a chair and ingested a given amount (16-17 ml kg body mass(-1)) of water (W) or solution containing 60, 120 or 180 mmol l(-1) Na(+) (60, 120 and 180Na trials) in 6 equal portions at 10 min intervals. To standardize their hydration status, subjects consumed the same meal and water 2 h before each trial. Drink trials were performed on separate days, and the order was randomized. The change in plasma volume (PV) from pre-drink status was estimated from the hemoglobin concentration and hematocrit every 30 min for 150 min after initiation of drinking.
  
  
  RESULTS
  Subjects began trials in a euhydrated state, as reflected by their plasma osmolality (in mmol l(-1): W, 289.4 ± 1.4; 60Na, 287.0 ± 3.5; 120Na, 287.6 ± 2.3; 180Na, 288.9 ± 3.3). At 120 min, PV had not increased from the pre-drink value in the W (-0.8 ± 4.5 %) or 60Na (2.4 ± 4.9 %) trials, but it increased to similar degrees in the 120Na (7.2 ± 4.6 %) and 180Na (9.4 ± 6.6 %) trials. No diarrhea was reported in the W or 60Na trials, but it was reported in the 120Na (n = 1) and 180Na (n = 6) trials.
  
  
  CONCLUSIONS
  Beverages containing 120 mmol l(-1) Na(+) induce hypervolemia with a minimum incidence of gastrointestinal problems.
authors: Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Tsukuba, 305-8574, Japan.
authors: Akira
authors: A
authors: Sugihara
authors: Naoto
authors: N
authors: Fujii
authors: Bun
authors: B
authors: Tsuji
authors: Kazuhito
authors: K
authors: Watanabe
authors: Takehiro
authors: T
authors: Niwa
authors: Takeshi
authors: T
authors: Nishiyasu
mesh_terms: D000328:Adult; D003967:Diarrhea / Q000209:etiology*; D060766:Drinking Water / Q000009:adverse effects* / Q000737:chemistry; D018495:Fluid Shifts / Q000502:physiology*; D006801:Humans; D008297:Male; D010953:Plasma Volume; D012146:Rest; D012964:Sodium / Q000097:blood; D012982:Sodium, Dietary / Q000009:adverse effects* / Q000032:analysis
chemical_list: D060766:Drinking Water; D012982:Sodium, Dietary; D012964:Sodium