title: Current formulas for water requirements produce different estimates.
abstract: BACKGROUND
  Weight-based and energy-based formulas are used to estimate the water requirements of patients receiving nutrition support, yet these formulas have not been validated nor quantitatively compared with one another. The objective of this study was to determine if there was agreement among commonly used formulas for estimating water requirements.
  
  
  METHODS
  This cross-sectional survey design was from the continuous National Health and Nutrition Examination Survey 1999-2004. To determine estimated water requirements for each participant, 2 weight-based formulas were used (30 mL/kg body weight and an adjusted body weight formula) and 3 energy-based formulas based on 1 mL/kcal (energy needs estimated by the Harris Benedict, Mifflin St Jeor, and National Research Council equations). Simple linear regression was performed between each pair of formulas to determine correlations. The regression line was then compared to the line of equality to determine agreement between pairs.
  
  
  RESULTS
  Although the 5 formulas were strongly correlated to each other (|r| > 0.7), they demonstrated poor agreement with one another with significant differences when the regression line was compared to the line of equality.
  
  
  CONCLUSIONS
  Current formulas that estimate the water requirements of patients receiving enteral nutrition and parenteral nutrition all compute a dissimilar quantity of water. The consequences of these estimates could result in major differences in water intake recommendations and prescriptions between patients or in the same patient, thus suggesting a need for improved standardization of practice for estimating water requirements in clinical practice.
authors.affiliation: Department of Dietetics and Nutrition, Florida International University, Miami, Florida, USA. stann001@fiu.edu
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Tannenbaum
authors.forename: Victoria H
authors.initials: VH
authors.lastname: Castellanos
authors.forename: Valerie
authors.initials: V
authors.lastname: George
authors.forename: Kristopher L
authors.initials: KL
authors.lastname: Arheart
mesh_terms: D000367:Age Factors; D001835:Body Weight; D003430:Cross-Sectional Studies; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008433:Mathematics; D009749:Nutrition Surveys; D009751:Nutritional Requirements; D018529:Nutritional Support / Q000379:methods / Q000592:standards*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012737:Sex Factors; D014867:Water / Q000008:administration & dosage*
chemical_list: D014867:Water