title: Evaluation of Equations for Predicting 24-Hour Urinary Sodium Excretion from Casual Urine Samples in Asian Adults.
abstract: The collection of 24-h urine samples for the estimation of sodium intake is burdensome, and the utility of spot urine samples in Southeast Asian populations is unclear.
  
  
  
  We aimed to assess the validity of prediction equations with the use of spot urine concentrations.
  
  
  
  A sample of 144 Singapore residents of Chinese, Malay, and Indian ethnicity aged 18-79 y were recruited from the Singapore Health 2 Study conducted in 2014. Participants collected urine for 24 h in multiple small bottles on a single day. To determine the optimal collection time for a spot urine sample, a 1-mL sample was taken from a random bottle collected in the morning, afternoon, and evening. Published equations and a newly derived equation were used to predict 24-h sodium excretion from spot urine samples.
  
  
  
  The mean ± SD concentration of sodium from the 24-h urine sample was 125 ± 53.4 mmol/d, which is equivalent to 7.2 ± 3.1 g salt. Bland-Altman plots showed good agreement at the group level between estimated and actual 24-h sodium excretion, with biases for the morning period of -3.5 mmol (95% CI: -14.8, 7.8 mmol; new equation) and 1.46 mmol (95% CI: -10.0, 13.0 mmol; Intersalt equation). A larger bias of 25.7 mmol (95% CI: 12.2, 39.3 mmol) was observed for the Tanaka equation in the morning period. The prediction accuracy did not differ significantly for spot urine samples collected at different times of the day or at a random time of day (P = 0.11-0.76).
  
  
  
  This study suggests that the application of both our own newly derived equation and the Intersalt equation to spot urine concentrations may be useful in predicting group means for 24-h sodium excretion in urban Asian populations.
authors.affiliation: Saw Swee Hock School of Public Health and clare_whitton@nuhs.edu.sg.
authors.forename: Clare
authors.initials: C
authors.lastname: Whitton
authors.affiliation: Saw Swee Hock School of Public Health and.
authors.forename: Gibson Ming Wei
authors.initials: GM
authors.lastname: Gay
authors.affiliation: Saw Swee Hock School of Public Health and.
authors.forename: Raymond Boon Tar
authors.initials: RB
authors.lastname: Lim
authors.affiliation: Saw Swee Hock School of Public Health and.
authors.forename: Linda Wei Lin
authors.initials: LW
authors.lastname: Tan
authors.affiliation: Saw Swee Hock School of Public Health and.
authors.forename: Wei-Yen
authors.initials: WY
authors.lastname: Lim
authors.affiliation: Saw Swee Hock School of Public Health and Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore; and Department of Nutrition, Harvard School of Public Health, Boston, MA.
authors.forename: Rob M
authors.initials: RM
authors.lastname: van Dam
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D005006:Ethnicity; D005260:Female; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D008875:Middle Aged; D012846:Singapore; D012982:Sodium, Dietary / Q000652:urine*; D016482:Urinalysis / Q000379:methods*; D055815:Young Adult
chemical_list: D012982:Sodium, Dietary
keywords: 24-hour urine collection; Asian population; equation; prediction; spot urine; urinary sodium