Body Weight-Specific Zinc Compartmental Masses in Girls Significantly Exceed Those Reported in Adults: A Stable Isotope Study Using a Kinetic Model

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Abstract
Maintaining optimal zinc status is important for normal growth and development in children, but minimal data are available regarding zinc metabolism in this age group. Our objectives were to utilize stable isotope–based compartmental modeling techniques to investigate zinc metabolism in healthy children; to expand a current stable isotope–based model to include red blood cell data; and to compare kinetic parameters in children with those previously reported in adults. Seven healthy girls, age 9.94 ± 0.79 y, received 1.1 mg of a 67zinc-enriched tracer orally and 0.5 mg of a 70zinc-enriched tracer intravenously. Blood, urine and fecal samples were collected for 6 d. Stable isotope enrichments were measured by thermal ionization magnetic sector mass spectrometry. A six-compartment model based on a model previously reported in adults was used; the model excluded red blood cell data. Body weight–corrected masses of the body zinc compartments derived using this model were significantly greater in children than those reported in adults. Modification of the model to include a red blood cell compartment increased the total identifiable zinc mass of the nongastrointestinal compartments by ∼2.5%. We conclude that compartmental modeling can be used to describe zinc kinetics in children, and that the body weight–corrected zinc pool masses are significantly greater in children than in adults.