title: Comparison of variability of urinary sodium, potassium, and calcium in free-living men.
abstract: The variability of 24-hour urinary sodium, potassium, and calcium excretion was studied in a sample of 22 Neapolitan men with mild blood pressure elevation. On 5 days within a 1-month period, 24-hour urine specimens were collected by each subject. The estimated ratio of intraindividual-to-interindividual variance was 1.12 for urinary sodium, 2.46 for urinary potassium, and 0.52 for urinary calcium. Based on these values, five 24-hour urine collections are necessary to reduce to less than 10% the diminution of the correlation coefficient between urinary sodium and another related variable; this number is substantially lower than that found in previous studies in a North American population sample, but similar to the one reported for Chinese population samples. Ten urinary collections are needed for potassium excretion. A different and more favorable situation is observed for 24-hour calcium excretion, as only two collections are necessary for the adequate characterization of individuals in a population.
authors.affiliation: Institute of Internal Medicine and Metabolic Disease, 2nd Medical School, University of Naples, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Siani
authors.forename: L
authors.initials: L
authors.lastname: Iacoviello
authors.forename: N
authors.initials: N
authors.lastname: Giorgione
authors.forename: R
authors.initials: R
authors.lastname: Iacone
authors.forename: P
authors.initials: P
authors.lastname: Strazzullo
mesh_terms: D000328:Adult; D000368:Aged; D002118:Calcium / Q000652:urine*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000652:urine*; D012964:Sodium / Q000652:urine*
chemical_list: D012964:Sodium; D011188:Potassium; D002118:Calcium