title: Intra- and interindividual iodine excretion in 24 hours in individuals in southern Brazil: a cross-sectional study.
abstract: OBJECTIVE
  To evaluate the variability of 24-hour urinary iodine (UI) excretion intra- and interindividually on three days of a week in healthy subjects, living in southern Brazil, and the correlation among the urinary excretion of iodine and sodium.
  
  
  METHODS
  Cross-sectional study, including 47 volunteers: 18 individuals with one, 15 individuals with two and 14 individuals with three 24-hour urine samples. Iodine, creatinine and Na(+) excretion in urine during 24-hour were measured.
  
  
  RESULTS
  Mean height, weight, BMI and 24-hour urinary excretion of creatinine were higher in men. UI and urinary sodium were correlated (n = 89, r = 0.524, p = 0.000). UI excretion varied widely, both inter- and intraindividually, on the 3 days of the week, but the mean excretion of UI was similar. In single individuals, the ratio between the maximum and minimum 24-hour UI excretion (m/m) ranged from 1.03 to 2.87, and the median coefficient of variation (CV) was 21% (P₂₅ = 7.0% and P₇₅ = 36.8%), with a range of 1%-51%. 24-hour UI excretion varied greatly among individuals on Sunday (CV = 47.5% and m/m = 7.75), Monday (CV = 38.7% and m/m = 4.60) and Thursday (CV = 40.4% and m/m = 4.50). UI was adequate in the group of 14 people, however, the UI excretion of two women suggested iodine intake persistently below that recommended by WHO.
  
  
  CONCLUSIONS
  The variability of 24-hour UI excretion on different days in the same individual is lower than that observed among individuals.
authors.affiliation: Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Milhoransa
authors.forename: Roberta
authors.initials: R
authors.lastname: Vanacor
authors.forename: Tania
authors.initials: T
authors.lastname: Weber Furlanetto
mesh_terms: D000328:Adult; D015992:Body Mass Index; D001938:Brazil; D003404:Creatinine / Q000652:urine; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000652:urine*; D008297:Male; D012737:Sex Factors; D012964:Sodium / Q000652:urine*; D013959:Thyroid Diseases / Q000175:diagnosis / Q000652:urine; D013997:Time Factors; D016482:Urinalysis
chemical_list: D007455:Iodine; D012964:Sodium; D003404:Creatinine