Changes in calcium kinetics in adolescent girls induced by high calcium intake

M. E. Wastney, B. R. Martin, M. Peacock, D. Smith, X. Y. Jiang, L. A. Jackman, C. M. Weaver

Research output: Contribution to journalArticlepeer-review

79 Scopus citations

Abstract

To identify the mechanism/s whereby calcium retention is increased by calcium intake in adolescent girls, kinetic studies were performed using stable calcium isotope tracers. Girls (n = 10; 12 ± 1 yr old, mean ± SD) were studied while on a controlled diet containing a low (21.2 mmol/day) and a high (47.4 mmol/day) calcium intake, in randomized order, using a cross-over design. Studies were separated by 1 month. Calcium tracers were administered after 1 week on the study diet, orally and iv; and serum, urine, and feces were collected for the following 14 days. Tracers were measured using fast atom bombardment mass spectrometry, and kinetic data were analyzed by compartmental modeling. Biochemical markers of bone turnover were measured in serum and urine samples. On high (compared with low) calcium intake, fractional absorption did not differ, absorbed calcium increased (19.6 ± 7.5 vs. 8.0 ± 2.5 mmol/day, mean ± SD, P < 0.001), calcium excreted in urine increased (2.8 ± 1.7 vs. 2.1 ± 1.1 mmol/day, P < 0.01), calcium retained in bone increased (14.5 ± 8.9 vs. 3.2 ± 3.6 mmol/day, P < 0.001), bone formation did not change, and bone resorption decreased by 32%. These changes, measured by kinetics, were corroborated by changes in markers of bone turnover. We conclude that increased bone retention of calcium, with high calcium intake in adolescent girls, is attributable to an increase in absorption and a decrease in bone resorption.

Original languageEnglish (US)
Pages (from-to)4470-4475
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Volume85
Issue number12
DOIs
StatePublished - 2000

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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