Bone Mineral Accretion in Young Children

This study seeks to understand bone mineral accrual in children 1 to 5 years of age. Many
young children have chronic medical conditions that threaten bone health and increase their
susceptibility to fractures. Over the last 10 years our team at Cincinnati Children's
Hospital Medical Center (CCHMC) has helped develop reference data that have enabled
clinicians to identify children 5 to 20 y with low bone density for age and optimize their
medical care. A glaring deficit is the inability to evaluate bone health of young children <
5 y due to lack of appropriate bone density reference data. This gap is problematic as there
are numerous clinical conditions (e.g., neuromuscular disease, cancer, glucocorticoid
treatment, extreme prematurity) that threaten bone health in this young age group.

The primary goal of our new study is to develop bone mass and density reference data to aid
identification of children 1 to 5 years of age with bone deficits. A first step is to
characterize the age-related changes in bone accrual at multiple skeletal sites and determine
when sex and race differences in bone mass and density emerge.

The second goal of this study is to assess the influence of growth, body composition, gross
motor skills and physical activity on bone mineral accrual in young children. In older
children, the need to account for growth and lean mass when interpreting bone measurements
has been demonstrated. The best way to do this in young children is unknown. Pronounced
changes in gross motor skills, locomotion and physical activity also occur during early
childhood. It is well appreciated that mechanical loads on the growing skeleton promote bone
mineral accrual. but how gross motor skills and physical activity impact bone development in
children 1 to 5 years of age is unknown. Understanding the impact of growth, body
composition, motor skill development, and physical activity on bone accrual in young children
is important for interpretation of clinical bone density measurements. These characteristics
are often affected in young children with chronic medical conditions.

This study will enroll 520 healthy children between 1 to 5 years of age; half will be
recruited at CCHMC and half at Children's Hospital of Philadelphia.

This study is unique since no previous studies have addressed these issues in children 1-5 y.
It is clinically relevant as findings will facilitate medical care of children with chronic
medical conditions that threaten bone health, and it will develop and validate novel methods
for bone and body composition assessment in this age range. It will also add generalizable
knowledge to enhance understanding of the growing skeleton, and its relationship to motor and
somatic development. Since poor bone mineral accrual can have lifelong consequences, this
study addresses the major public health concern of osteoporosis.

Inclusion Criteria:

- We will enroll healthy, normally growing children free from medical conditions that
may affect bone or growth between the ages of 1-5 years.

Exclusion Criteria:

- Weight, length and weight-for-length outside ± 2 Standard Deviations of the 2006 World
Health Organization growth standard for ages 1 to 2 y and the 3rd to 97th percentiles
of the Centers for Disease Control 2000 growth reference for ages ≥ 2 years as
recommended;84 chronic medical conditions affecting bone density (e.g., cancer,
kidney, gastrointestinal, musculoskeletal or endocrine disorder); chronic use of
medications that affect bone (glucocorticoids, anti-epileptics, or hormones); prior
fracture; dietary restrictions; preterm birth (<37 wk gestation) and low birth weight
(<2500 g).