Bone Density in the Obese Child: Clinical Considerations and Diagnostic Challenges

Abstract

The prevalence of obesity in children has reached epidemic proportions. Concern about bone health in obese children, in part, derives from the potentially increased fracture risk associated with obesity. Additional risk factors that affect bone mineral accretion, may also contribute to obesity, such as low physical activity and nutritional factors. Consequences of obesity, such as inflammation, insulin resistance, and non-alcoholic fatty liver disease, may also affect bone mineral acquisition, especially during the adolescent years when rapid increases in bone contribute to attaining peak bone mass. Further, numerous pediatric health conditions are associated with excess adiposity, altered body composition, or endocrine disturbances that can affect bone accretion. Thus, there is a multitude of reasons for considering clinical assessment of bone health in an obese child. Multiple diagnostic challenges affect the measurement of bone density and its interpretation. These include greater precision error, difficulty in positioning, and the effects of increased lean and fat tissue on bone health outcomes. Future research is required to address these issues to improve bone health assessment in obese children.

Keywords: Body composition; Children; Dual-energy X-ray absorptiometry; Fracture; Obesity; Peripheral quantitative computed tomography.

Figure 1

Age and sex distribution of total body less head bone mineral content for children ages 5 to 20 years from the Bone Mineral Density in Childhood Study. Adapted from Zemel et al. [103].

Figure 2. DXA Whole Body Scans in (A) an Obese Child and a (B) Healthy Weight Child of Similar Age and Height

Whole body DXA scans of two 14 year old girls of similar height, one who is obese and the other who is healthy weight (BMI<85^th percentile). Shown are the body composition results of the total body and sub-regions.

Figure 2. DXA Whole Body Scans in (A) an Obese Child and a (B) Healthy Weight Child of Similar Age and Height

Whole body DXA scans of two 14 year old girls of similar height, one who is obese and the other who is healthy weight (BMI<85^th percentile). Shown are the body composition results of the total body and sub-regions.

Figure 3. pQCT Scans of the Distal Tibia (3% and 38% of tibia length) in (A) an Obese Child and a (B) Healthy Weight Child of Similar Age and Height

pQCT scans of the distal tibia at the 3% and 38% sites of two 14 year old girls of similar height (same as above), one who is obese and the other who is healthy weight (BMI<85^th percentile). Shown are the bone and body composition results.

Figure 3. pQCT Scans of the Distal Tibia (3% and 38% of tibia length) in (A) an Obese Child and a (B) Healthy Weight Child of Similar Age and Height

pQCT scans of the distal tibia at the 3% and 38% sites of two 14 year old girls of similar height (same as above), one who is obese and the other who is healthy weight (BMI<85^th percentile). Shown are the bone and body composition results.