title: Variables related to urinary calcium excretion in young girls.
abstract: The relations among dietary and calcium kinetic factors and 24-h urinary mineral excretion were evaluated in a group of 89 healthy girls (51 white and 38 black) aged 4.9-16.7 years. Nutrient intakes were calculated for each participant using a weighed intake of all food and beverage on the day of the 24-h urine collection study and two subsequent 24-h food records. A significant relation was noted between urinary calcium and sodium excretion (r = 0.55; p < 0.0001). No significant relations were found between urinary calcium and (a) calcium intake (r = 0.08), (b) protein intake (r = 0.14), or (c) phosphorus intake (r = 0.11). Urinary calcium was not significantly related to fractional calcium absorption (r = 0.03) or net calcium absorption (r = 0.11), but was significantly associated with the bone calcium deposition rate (r = 0.24; p < 0.03). Using a multiple regression model, both urinary sodium and the bone calcium deposition rate were independent predictors of urinary calcium excretion in this population (r = 0.57; p = 0.0001). A substantial number of the children in this population had urinary calcium excretion > 4 mg/kg/day (12%). The incidence of hypercalciuria differed between the racial groups and was markedly higher in the white than in the black children (17.6 vs. 5.3%). Over a range of usual calcium intakes, during the rapid-bone-growth period in childhood and early adolescence, urinary calcium appears relatively unaffected by calcium intake and is most strongly associated with urinary sodium levels.
authors.affiliation: U.S. Department of Agriculture (USDA)/Agricultural Research Service (ARS), Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: K O
authors.initials: KO
authors.lastname: O'Brien
authors.forename: S A
authors.initials: SA
authors.lastname: Abrams
authors.forename: J E
authors.initials: JE
authors.lastname: Stuff
authors.forename: L K
authors.initials: LK
authors.lastname: Liang
authors.forename: T R
authors.initials: TR
authors.lastname: Welch
mesh_terms: D000042:Absorption; D000293:Adolescent; D000367:Age Factors; D044383:Black People; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000652:urine*; D002127:Calcium Isotopes; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008903:Minerals / Q000378:metabolism / Q000652:urine; D011627:Puberty / Q000652:urine; D012044:Regression Analysis; D012964:Sodium / Q000378:metabolism / Q000652:urine; D013781:Texas; D044465:White People; D001741:Black or African American
chemical_list: D002127:Calcium Isotopes; D002136:Calcium, Dietary; D008903:Minerals; D012964:Sodium; D002118:Calcium