title: Daily sodium and potassium excretion can be estimated by scheduled spot urine collections.
abstract: OBJECTIVE
  The evaluation of sodium and potassium intake is part of the optimal management of hypertension, metabolic syndrome, renal stones, and other conditions. To date, no convenient method for its evaluation exists, as the gold standard method of 24-hour urine collection is cumbersome and often incorrectly performed, and methods that use spot or shorter collections are not accurate enough to replace the gold standard. The aim of this study was to evaluate the correlation and agreement between a new method that uses multiple-scheduled spot urine collection and the gold standard method of 24-hour urine collection.
  
  
  METHODS
  The urine sodium or potassium to creatinine ratios were determined for four scheduled spot urine samples. The mean ratios of the four spot samples and the ratios of each of the single spot samples were corrected for estimated creatinine excretion and compared to the gold standard.
  
  
  RESULTS
  A significant linear correlation was demonstrated between the 24-hour urinary solute excretions and estimated excretion evaluated by any of the scheduled spot urine samples. The correlation of the mean of the four spots was better than for any of the single spots. Bland-Altman plots showed that the differences between these measurements were within the limits of agreement.
  
  
  CONCLUSIONS
  Four scheduled spot urine samples can be used as a convenient method for estimation of 24-hour sodium or potassium excretion.
authors.affiliation: Department of Nephrology, Assaf Harofeh Medical Center, Zerifin, Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel.
authors.forename: Keren
authors.initials: K
authors.lastname: Doenyas-Barak
authors.forename: Ilia
authors.initials: I
authors.lastname: Beberashvili
authors.forename: Adina
authors.initials: A
authors.lastname: Bar-Chaim
authors.forename: Zhan
authors.initials: Z
authors.lastname: Averbukh
authors.forename: Ofir
authors.initials: O
authors.lastname: Vogel
authors.forename: Shai
authors.initials: S
authors.lastname: Efrati
mesh_terms: D000328:Adult; D000368:Aged; D002712:Chlorides / Q000652:urine; D003404:Creatinine / Q000652:urine; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000652:urine*; D012015:Reference Standards; D012964:Sodium / Q000652:urine*; D016482:Urinalysis / Q000379:methods; D059349:Urine Specimen Collection / Q000379:methods*; D055815:Young Adult
chemical_list: D002712:Chlorides; D012964:Sodium; D003404:Creatinine; D011188:Potassium