Pediatric DXA: clinical applications

Normal bone mineral accrual requires adequate dietary intake of calcium, vitamin D and other nutrients; hepatic and renal activation of vitamin D; normal hormone levels (thyroid, parathyroid, reproductive and growth hormones); and neuromuscular functioning with sufficient stress upon the skeleton to induce bone deposition. The presence of genetic or acquired diseases and the therapies that are used to treat them can also impact bone health. Since the introduction of clinical DXA in pediatrics in the early 1990s, there has been considerable investigation into the causes of low bone mineral density (BMD) in children. Pediatricians have also become aware of the role adequate bone mass accrual in childhood has in preventing osteoporotic fractures in late adulthood. Additionally, the availability of medications to improve BMD has increased with the development of bisphosphonates. These factors have led to the increased utilization of DXA in pediatrics. This review summarizes much of the previous research regarding BMD in children and is meant to assist radiologists and clinicians with DXA utilization and interpretation

Fitness of Children with Standard-Risk Acute Lymphoblastic Leukemia During Maintenance Therapy: Response to a Home-Based Exercise and Nutrition Program

Background: Altered nutrient intake and decreased exercise in response to cancer therapies and their side effects, particularly corticosteroids, may be key factors in the increased body weight and differences in physical fitness reported in survivors of childhood acute lymphoblastic leukemia (ALL). Purpose: To assess (1) the effect of a home-based nutrition and exercise intervention program on cardiovascular fitness, strength, and flexibility in children with ALL during maintenance therapy and (2) the feasibility of conducting and evaluating a home-based exercise and nutrition program in this patient population. Design: Children ages 4 to 10 years with standard-risk ALL were randomized when starting maintenance therapy to a 12-month home-based exercise and nutrition program (n=6, 3 males/3 females) or control (n=7, 4 males/3 females) group. Assessment of anthropometrics, dietary intake, physical activity, and fitness was performed at baseline and 6 and 12 months of study. Results: Although age, body size, and nutrient intakes were similar between both subject groups at 0, 6, and 12 months, exercise and nutrition program children had greater improvement in physical activity and cardiovascular fitness between 6 and 12 months than control children. Conclusions: These results suggest that a home-based exercise intervention during maintenance therapy encouraged greater physical activity and improved cardiovascular fitness in children with standard-risk ALL. Further investigation involving larger populations of children with ALL is warranted

Mid-arm circumference is a reliable method to estimate adiposity in preterm and term infants

BACKGROUND: Premature birth is associated with increased adipose deposition after birth. Standard anthropometry (body weight, length, and head circumference) may not adequately assess fat deposition. Validated methods to assess adiposity are needed to optimize growth quality in preterm infants. The purpose of this study was to identify covariates of infant body fat. METHODS: Air displacement plethysmography (ADP), standard anthropometry, and body circumferences were measured at hospital discharge in preterm (n = 28; 31-35 wk postmenstrual age (PMA)) and term (n = 28; 38-41 wks PMA) infants. RESULTS: Body weight, length, and head circumference were lower for preterm infants (P \u3c 0.05) at hospital discharge compared with that of term infants. Despite smaller body size and younger PMA, preterm infant percent body fat (%BF) by ADP was 12.33 +/- 4.15% vs. 9.64 +/- 4.01% in term infants (P = 0.01). Mid-arm circumference (MAC) is a covariate of %BF in both preterm and term infants (adjusted R(2) = 0.49; P \u3c 0.001). In preterm infants alone, MAC accounted for 60.4% of the variability of percent body fat (%BF) by ADP (P \u3c 0.01). CONCLUSIONS: Preterm infants have increased body fat deposition as they approach term-corrected age, and MAC is a reliable, low-cost measure for monitoring infant body fat deposition in preterm and term infants