THE RELATIONSHIP BETWEEN MAGNESIUM AND CALCIUM KINETICS IN 9-YEAR-OLDTO 14-YEAR-OLD CHILDREN

Few measurements of magnesium (Mg) kinetics have been performed, espec ially in children and adolescents, Simultaneous Mg and calcium (Ca) ki netics following intravenous administration of Ca-42 and Mg-25 were me asured in 22 children (10 boys and 12 girls) 9-14 years of age, Kineti c values, including the body pool masses (Mg-Comp and Ca-Comp for the Mg and Ca compartment masses, respectively) and bone/tissue (hard and soft tissue) Ca and Mg deposition rates (V-o+(Ca) and V-o+(Mg), respec tively) were calculated using the Simulation, Analysis, and Modeling ( SAAM) program, No significant differences were found between males and females (p > 0.3 for each comparison) for pool masses or deposition r ates. V-o+(Ca) and V-o+(Mg) were highly correlated (r = 0.78, p < 0.00 1). V-o+(Mg) but not V-o+(Ca), was closely correlated with body weight (r = 0.55, p < 0.01 and r = 0.16, p = 0.47, respectively), Similarly, Mg-Comp was more closely correlated with body weight (r = 0.76, p < 0 .01) than Ca-Comp (r = 037,p = 0.10), Neither V-o+(Ca) nor Ca-Comp inc reased significantly over the age range studied, However, V-o+(Mg) and Mg-Comp were significantly positively correlated with age, These find ings demonstrate differences in regulation of Ca versus Mg kinetics by young adolescents, These differences may be related to the greater ut ilization of Mg for muscle and soft tissue growth, The close relations hip between V-o+(Mg) and body weight suggests that the current practic e of relating Mg intake requirements to body weight, as well as age, i s appropriate for young adolescents.