Mario Skugor

Relation of Nutrition, Body Composition and Physical Activity to Skeletal Development: A Cross-Sectional Study in Preadolescent Females

OBJECTIVE To examine the relation of anthropometric and growth parameters (weight, stature, body composition, age, and skeletal age), nutritional factors, and physical activity to the total body and radius bone mineral density and content and radiogrammetry parameters of the second metacarpal. STUDY DESIGN The study was a cross-sectional evaluation of 456 healthy, Caucasian girls, ages 8 to 13 years. Multiple regression models were created based on Cp statistics to determine the association between bone parameters and various independent variables. RESULTS Mean calcium intake was 956+/-381 mg/day, about 20% below the RDA of 1200 mg/day and about 36% below the threshold intake of approximately 1500 mg/day. The most significant predictors for total body and radius bone mineral density were corresponding bone areas, lean body mass, body fat, skeletal age, dietary calcium, and stature (only for total body) with corresponding R2(adjusted) of 48% and 36%. The total body and radius bone mineral content was positively associated with corresponding bone areas, lean body mass, body fat, calcium intake, and skeletal age with corresponding R2(adjusted) of 86% and 72%. Energy expenditure (corrected for BMI) was stratified into quartiles and bone mass parameters were distributed accordingly. A statistically significant difference in total body and radius bone mineral density and content was noted between the fourth and lower quartiles (ANOVA, p<0.05 to p<0.0001). CONCLUSION The most significant predictors of bone mass in preadolescent females evaluated in this study are bone area, lean body mass, body fat, skeletal age and dietary calcium.

Skeletal age as a determinant of bone mass in preadolescent females

Abstract Objective. To evaluate the association between chronological age, skeletal age, pubertal stage, and basic anthropometry with bone mass of the total body, forearm, and second metacarpal bone in 456 healthy Caucasian females, aged 8–13 years. Design. Total body and forearm bone measurements were performed by dual X-ray absorptiometry, while bone mass of the second metacarpal was assessed by radiogrammetry. Skeletal age (SA) was assessed by the FELS method and pubertal stage was self-determined by selecting corresponding illustrations of breast and pubic hair development. The Cpcriterion was used to select the best multiple regression model containing the subset of independent variables with the least bias and best predictive ability for each of the measured bone mass variables. Results. Of all the independent variables, weight, stature, and SA emerged as the most significant predictors for almost all the bone mass variables. Multiple regression models were created based on the Cpcriterion with the resulting R2 (adjusted) for bone mineral content of total body, proximal forearm, ultradistal forearm, length of second metacarpal, as well as of total, medullary, and cortical areas: 0.793, 0.523, 0.390, 0.602, 0.232, 0.073, and 0.264, respectively. The measured bone variables were also regressed on SA using either quadratic or linear equations, depending on the shape of the cubic splines used for the best curve fitting. Significant positive association (p<0.0001) of SA and each of the bone variables was noted, the highest being with bone mineral density and content of total body (R2=0.176, 0.338) and proximal and ultradistal forearm (R2=0.216, 0.203, 0.106, 0.201), respectively, as well as with the length of the second metacarpal bone (R2=0.339). Chronological age and pubertal stage did not have statistically significant predictive abilities for bone mass variables in the multiple regression models. Conclusions. We conclude that skeletal age is a powerful determinant of bone mass in children. It can be used as the criterion for the selection of a biologically homogeneous population with regard to bone mass. This may be important for the design of intervention studies targeting bone mass of children and adolescents.

Comparison of Absorptiometric Evaluations from Total-Body and Local-Region Skeletal Scans

The most common measurement sites for dual-energy absorptiometry (DXA) in clinical practice are posteroanterior (PA) spine and femur. However, other skeletal regions may provide different bone density information. The purpose of this study was to establish the least number of DXA measurements needed to obtain complete information about bone. A total of 262 normal female subjects, 8-50, were measured on a Lunar DPX-L scanner under total body, PA spine, lateral spine, and femur protocol. Forearm measurements were performed with a Lunar SP2 single-photon absorptiometry scanner. The various measurements were compared based on a linear regression model. The correlation coefficients for bone mineral density (BMD) between adjacent vertebrae were 0.92-0.95, and the associated standard errors of the estimate (SEE) were 4.5-5.5%. Total-body BMD can best predict BMD of the trunk, arms, and legs (SEE<4.3%), but least that of the lateral view of the spine (SEE>13.9%). BMD values of the leg from total-body scans predict those from the femoral neck with an error of 9.0%, and those of the trochanteric region with 11.1%. The error between adjacent vertebrae (6%) is considered acceptable, then a total-body measurement combined with a lateral view of the spine and a femur scan are adequate.

Skeletal Development in Young Females: Endogenous Versus Exogenous Factors

The most critical period in skeletal development is during the time of the most rapid bone modeling and turnover of the adolescence. The process of bone modeling that takes place from birth until the cessation of longitudinal bone growth is characterized by changes in the volume and the shape of the bones. Thereafter, bone tissue within the existing skeletal structure is continuously being formed and resorbed with minimal change in bone size through the remodeling process (1). From infancy through late adolescence the activity of bone formation predominates, resulting in a steady accumulation of bone mass. On average, most of the skeletal mass is accumulated by the age of 18 (Fig. 3.1) (2, 3). Thereafter, there is a minimal change in bone mass and density with age up to the time of menopause. Some skeletal sites begin to lose bone immediately after the age of 18 (proximal femur and trabecular bone in the vertebrae), and the other sites show continuous apposition of bone up to the time of menopause (forearm and total spine) (3).

Effects of Long-Term Calcium Supplementation on Iron Status in Adolescent Females

Abstract LEARNING OUTCOME: The 4-year calcium supplementation did not affect serum ferritin and iron deficiency anemia indices in adolescent females. The recent recommendations of National Institutes of Health for increasing calcium (Ca) intake in adolescent females to 1200-1500mg/day raised a concern about its effects on other minerals, namely iron. The previous studies examining the effects of Ca supplementation on iron status in humans resulted in mixed conclusions. The objective of our study was to investigate the effects of Ca supplementation on iron status during a 4-year period. A sample of 354 healthy, Caucasian females were enrolled in the study at the average age of 10.8 y; one half was randomly assigned to receive 1000mg/d Ca as Ca citrate malate and another half placebo. Blood was drawn once a year and serum ferritin was analyzed by the automated procedure (Hitachi Analyzer), while red blood cell indices and hemoglobin were determined at the end of the 4-year follow-up. The subjects completed 3-day dietary records annualy, which were analyzed on Nutritionist III. The average annual compliance with pill intake was 70%. Table presents yearly data (mean±SD): There was no statistical difference between placebo and Ca supplemented group in corresponding hemoglobin (13.4±0.8 vs. 13.2±0.9, p=0.1), hematocrit (38.5±2.4 vs. 37.9±2.5, p=0.2), red blood cell count (4.4±0.3 vs. 4.4±0.3, p=0.3), mean corpuscular volume (86.6±3.5 vs. 86.5±4.0, p=0.8), and mean corpuscular hemoglobin concentration (34.8±0.6 vs. 34.7±0.7, p=0.1). Our results indicate that long-term (4 years) calcium supplementation in adolescent females has no effect on iron stores, as measured by serum ferritin, or indices of iron deficiency anemia.