title: Higher urinary sodium, a proxy for intake, is associated with increased calcium excretion and lower hip bone density in healthy young women with lower calcium intakes.
abstract: We assessed 24-h urinary sodium (Na) and its relationship with urinary calcium (Ca) and areal bone mineral density (aBMD) at the whole body, lumbar spine and total hip in a cross-sectional study. 102 healthy non-obese women completed timed 24-h urine collections which were analyzed for Na and Ca. Dietary intakes were estimated using a validated food frequency questionnaire. Participants were grouped as those with lower vs. higher calcium intake by median split (506 mg/1000 kcal). Dietary Na intake correlated with 24-h urinary loss. Urinary Na correlated positively with urinary Ca for all participants (r = 0.29, p < 0.01) and among those with lower (r = 0.37, p < 0.01) but not higher calcium intakes (r = 0.19, p = 0.19). Urinary Na was inversely associated with hip aBMD for all participants (r = -0.21, p = 0.04) and among women with lower (r = -0.36, p < 0.01) but not higher (r = -0.05, p = 0.71) calcium intakes. Urinary Na also entered a regression equation for hip aBMD in women with lower Ca intakes, contributing 5.9% to explained variance. In conclusion, 24-h urinary Na (a proxy for intake) is associated with higher urinary Ca loss in young women and may affect aBMD, particularly in those with lower calcium intakes.
authors.affiliation: Diabetes Education Centre, Ross Memorial Hospital, 10 Angeline St N, Lindsay, Ontario K9V 4M8, Canada.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Bedford
authors.affiliation: University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Susan I
authors.identifier: 0000-0001-8701-7152
authors.initials: SI
authors.lastname: Barr
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015415:Biomarkers / Q000652:urine; D015519:Bone Density / Q000502:physiology*; D002118:Calcium / Q000008:administration & dosage / Q000652:urine*; D003430:Cross-Sectional Studies; D004032:Diet; D005260:Female; D006615:Hip / Q000000981:diagnostic imaging*; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D012964:Sodium / Q000008:administration & dosage / Q000652:urine*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D012964:Sodium; D002118:Calcium