Calcium requirement distribution via bone growth modeling

Michael R Lawlor, Purdue University


This dissertation focuses on estimating calcium requirements using bone growth data in adolescents. We estimate the peak rate of growth of bone and the variability of this peak growth rate to provide Dietary Reference Intakes (DRIs) for calcium. The specific DRIs of interest are Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA). Included within the analysis is the age at which this peak occurs. A generalized logistic curve uses age as the explanatory variable to predict total body bone mineral content (TBBMC), which is the mass of the mineral content within the bones in the entire body. The population of subjects of interest is males and females aged 9 through 18. We estimate the distribution of these growth curves across individuals. We assume that this distribution is specified by parameters that are jointly Normal. Parameters of these models are estimated using the Saskatchewan data set from Bailey et al. The subsequent DRI analysis uses values at the peak rate of growth as well as an average rate of growth over the current age guidelines within the factorial method for both males and females. Additionally, the DRI analysis compares the use of a factorial method versus different models to relate the amount of calcium retained to the amount of calcium intake required. Future work will investigate the incorporation of race, body mass index, height, weight, and other anthropomorphic variables. For this portion, material will come from the Saskatchewan, Iowa, and Camp Calcium data sets.




McCabe, Purdue University.

Subject Area

Statistics|Health sciences

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