The Relationship Between Magnesium and Calcium Kinetics in 9- to 14-Year-Old Children

Abstract

Few measurements of magnesium (Mg) kinetics have been performed, especially in children and adolescents. Simultaneous Mg and calcium (Ca) kinetics following intravenous administration of 42Ca and 25Mg were measured in 22 children (10 boys and 12 girls) 9-14 years of age. Kinetic values, including the body pool masses (MgComp and CaComp for the Mg and Ca compartment masses, respectively) and bone/tissue (hard and soft tissue) Ca and Mg deposition rates (Vo+Ca and Vo+Mg respectively) 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 rates. Vo+Ca and Vo+Mg were highly correlated (r = 0.78, p < 0.001). Vo+Mg but not Vo+Ca, was closely correlated with body weight (r = 0.55, p < 0.01 and r = 0.16, p = 0.47, respectively). Similarly, MgComp was more closely correlated with body weight (r = 0.76, p < 0.01) than CaComp (r = 037,p = 0.10). Neither Vo+Ca nor CaComp increased significantly over the age range studied. However, Vo+Mg and MgComp were significantly positively correlated with age. These findings demonstrate differences in regulation of Ca versus Mg kinetics by young adolescents. These differences may be related to the greater utilization of Mg for muscle and soft tissue growth. The close relationship between Vo+Mg and body weight suggests that the current practice of relating Mg intake requirements to body weight, as well as age, is appropriate for young adolescents.

Magnesium Metabolism in 4-Year-Old to 8-Year-Old Children

“…This was followed by studies conducted at our center involving young adolescents . In these studies, we found a close relationship between whole‐body fat‐free mass and Mg kinetics . We were able to confirm the need for a full 72‐hour urine collection time period to accurately assess Mg absorption.…”

“…Fractional absorption of Mg was calculated as the relative recovered oral versus intravenous isotope in a 72‐hour urine specimen collected starting at the time of the tracer administration . Total Mg absorption was calculated as the product of intake and fractional absorption.…”

“…Modern stable isotope studies are expensive and only a handful of centers have the technical capacity to perform and analyze them. Most estimates for dietary Mg requirements were made using interpolation of data from infants and adolescents …”

Magnesium Intake, C-Reactive Protein, and Muscle Mass in Adolescents

“…One study in seventeen youth athletes observed that low magnesium intake was associated with low muscle mass [ 45 ]. The relationship between magnesium intake and muscle mass is particularly important in adolescents because their growth of muscle and soft tissue demand greater magnesium concentration, which further highlights the public health implications of low magnesium intake [ 46 ]. Mechanistically, magnesium is suggested to improve muscle mass via reducing serum parathyroid hormone (PTH).…”

Calcium requirements and metabolism in Chinese-American boys and girls

“…Calcium intake effects on calcium kinetic parameters were not statistically different for boys and girls, but there were sex differences in bone turnover rates in contrast to a study in prepubertal children. (27)…”