title: Evaluation of using spot urine to replace 24 h urine sodium and potassium excretions.
abstract: OBJECTIVE
  The most accurate method to estimate Na and K intakes is to determine 24 h urinary excretions of these minerals. However, collecting 24 h urine is burdensome. Therefore it was studied whether spot urine could be used to replace 24 h urine samples.
  
  
  METHODS
  Participants collected 24 h urine and kept one voiding sample separate. Na, K and creatinine concentrations were analysed in both 24 h and spot urine samples. Also 24 h excretions of Na and K were predicted from spot urine concentrations using the Tanaka and Danish methods.
  
  
  METHODS
  In 2011 and 2012, urine samples were collected and brought to the study centre at Wageningen University, the Netherlands.
  
  
  METHODS
  Women (n 147) aged 19-26 years.
  
  
  RESULTS
  According to p-aminobenzoic acid excretions, 127 urine collections were complete. Correlations of Na:creatinine, K:creatinine and Na:K between spot urine and 24 h urine were 0·68, 0·57 and 0·64, respectively. Mean 24 h Na excretion predicted with the Tanaka method was higher (difference 21·2 mmol/d, P<0·001) than the measured excretion of 131·6 mmol/d and mean 24 h Na excretion predicted with the Danish method was similar (difference 3·2 mmol/d, P=0·417) to the measured excretion. The mean 24 h K excretion predicted with the Tanaka method was higher (difference 13·6 mmol/d, P<0·001) than the measured excretion of 66·8 mmol/d. Bland-Altman plots showed large individual differences between predicted and measured 24 h Na and K excretions.
  
  
  CONCLUSIONS
  The ratios of Na:creatinine and K:creatinine in spot urine were reasonably well associated with their respective ratios in 24 h urine and appear to predict mean 24 h Na excretion of these young, Caucasian women.
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Eveline J C
authors.initials: EJ
authors.lastname: Hooft van Huysduynen
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Paul J M
authors.initials: PJ
authors.lastname: Hulshof
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Linde
authors.initials: L
authors.lastname: van Lee
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Anouk
authors.initials: A
authors.lastname: Geelen
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Edith J M
authors.initials: EJ
authors.lastname: Feskens
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: van 't Veer
authors.affiliation: 2Division of Strategic Communication,Wageningen University,Wageningen,The Netherlands.
authors.forename: Cees J M
authors.initials: CJ
authors.lastname: van Woerkum
authors.affiliation: 1Division of Human Nutrition,Wageningen University,PO Box 8129 (Bode 62, HNE),6700 EV Wageningen,The Netherlands.
authors.forename: Jeanne H M
authors.initials: JH
authors.lastname: de Vries
mesh_terms: D000328:Adult; D062365:Aminobenzoates / Q000652:urine; D015415:Biomarkers / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000652:urine; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D016014:Linear Models; D009426:Netherlands; D011188:Potassium / Q000652:urine*; D012964:Sodium / Q000652:urine*; D016482:Urinalysis / Q000379:methods*; D044465:White People; D055815:Young Adult
chemical_list: D062365:Aminobenzoates; D015415:Biomarkers; D012964:Sodium; D003404:Creatinine; D011188:Potassium